diff --git a/locale/circuitpython.pot b/locale/circuitpython.pot
index e09df9d17818a..20425d2d77ff9 100644
--- a/locale/circuitpython.pot
+++ b/locale/circuitpython.pot
@@ -186,6 +186,14 @@ msgstr ""
 msgid "%q must be 1 when %q is True"
 msgstr ""
 
+#: ports/raspberrypi/common-hal/audioi2sin/I2SIn.c
+msgid "%q must be 16, 24, or 32"
+msgstr ""
+
+#: shared-bindings/audioi2sin/I2SIn.c
+msgid "%q must be 8, 16, 24, or 32"
+msgstr ""
+
 #: py/argcheck.c shared-bindings/gifio/GifWriter.c
 #: shared-module/gifio/OnDiskGif.c
 msgid "%q must be <= %d"
@@ -660,6 +668,7 @@ msgid "Below minimum frame rate"
 msgstr ""
 
 #: ports/raspberrypi/common-hal/audiobusio/I2SOut.c
+#: ports/raspberrypi/common-hal/audioi2sin/I2SIn.c
 msgid "Bit clock and word select must be sequential GPIO pins"
 msgstr ""
 
@@ -804,7 +813,7 @@ msgstr ""
 msgid "Cannot pull on input-only pin."
 msgstr ""
 
-#: shared-bindings/audiobusio/PDMIn.c
+#: shared-bindings/audiobusio/PDMIn.c shared-bindings/audioi2sin/I2SIn.c
 msgid "Cannot record to a file"
 msgstr ""
 
@@ -926,7 +935,7 @@ msgstr ""
 msgid "Deep sleep pins must use a rising edge with pulldown"
 msgstr ""
 
-#: shared-bindings/audiobusio/PDMIn.c
+#: shared-bindings/audiobusio/PDMIn.c shared-bindings/audioi2sin/I2SIn.c
 msgid "Destination capacity is smaller than destination_length."
 msgstr ""
 
@@ -1807,6 +1816,7 @@ msgid "Parameter error"
 msgstr ""
 
 #: ports/espressif/common-hal/audiobusio/__init__.c
+#: ports/espressif/common-hal/audioi2sin/I2SIn.c
 msgid "Peripheral in use"
 msgstr ""
 
@@ -3510,6 +3520,11 @@ msgstr ""
 msgid "invalid cert"
 msgstr ""
 
+#: shared-bindings/audioi2sin/I2SIn.c
+#, c-format
+msgid "invalid destination buffer, must be an array of type: %c"
+msgstr ""
+
 #: shared-bindings/bitmaptools/__init__.c
 #, c-format
 msgid "invalid element size %d for bits_per_pixel %d\n"
diff --git a/ports/espressif/Makefile b/ports/espressif/Makefile
index 8faad5fb5def2..b0ba572d438a7 100644
--- a/ports/espressif/Makefile
+++ b/ports/espressif/Makefile
@@ -592,6 +592,10 @@ ifneq ($(CIRCUITPY_AUDIOBUSIO),0)
 CHIP_COMPONENTS += esp_driver_i2s
 endif
 
+ifneq ($(CIRCUITPY_AUDIOI2SIN),0)
+CHIP_COMPONENTS += esp_driver_i2s
+endif
+
 ifneq ($(CIRCUITPY_BLEIO_NATIVE),0)
 SRC_C += common-hal/_bleio/ble_events.c
 endif
diff --git a/ports/espressif/boards/adafruit_sparkle_motion/pins.c b/ports/espressif/boards/adafruit_sparkle_motion/pins.c
index d78c1e1c4c75c..f22cb50608d1f 100644
--- a/ports/espressif/boards/adafruit_sparkle_motion/pins.c
+++ b/ports/espressif/boards/adafruit_sparkle_motion/pins.c
@@ -46,6 +46,10 @@ static const mp_rom_map_elem_t board_module_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR_SIG4), MP_ROM_PTR(&pin_GPIO23) },
     { MP_ROM_QSTR(MP_QSTR_D23), MP_ROM_PTR(&pin_GPIO23) },
 
+    { MP_ROM_QSTR(MP_QSTR_D25), MP_ROM_PTR(&pin_GPIO25) },
+    { MP_ROM_QSTR(MP_QSTR_D26), MP_ROM_PTR(&pin_GPIO26) },
+    { MP_ROM_QSTR(MP_QSTR_D33), MP_ROM_PTR(&pin_GPIO33) },
+
     { MP_ROM_QSTR(MP_QSTR_TX), MP_ROM_PTR(&pin_GPIO9) },
     { MP_ROM_QSTR(MP_QSTR_D9), MP_ROM_PTR(&pin_GPIO9) },
 
diff --git a/ports/espressif/common-hal/audioi2sin/I2SIn.c b/ports/espressif/common-hal/audioi2sin/I2SIn.c
new file mode 100644
index 0000000000000..9953f221b7f35
--- /dev/null
+++ b/ports/espressif/common-hal/audioi2sin/I2SIn.c
@@ -0,0 +1,327 @@
+// This file is part of the CircuitPython project: https://circuitpython.org
+//
+// SPDX-FileCopyrightText: Copyright (c) 2026 Tim Cocks for Adafruit Industries
+//
+// SPDX-License-Identifier: MIT
+
+#include <string.h>
+
+#include "bindings/espidf/__init__.h"
+
+#include "common-hal/audioi2sin/I2SIn.h"
+#include "py/runtime.h"
+#include "shared-bindings/audioi2sin/I2SIn.h"
+#include "shared-bindings/microcontroller/Pin.h"
+
+#include "driver/i2s_std.h"
+
+#if CIRCUITPY_AUDIOI2SIN
+
+void common_hal_audioi2sin_i2sin_construct(audioi2sin_i2sin_obj_t *self,
+    const mcu_pin_obj_t *bit_clock, const mcu_pin_obj_t *word_select,
+    const mcu_pin_obj_t *data, const mcu_pin_obj_t *main_clock,
+    uint32_t sample_rate, uint8_t bit_depth, uint8_t output_bit_depth,
+    bool mono, bool left_justified, bool samples_signed) {
+
+    i2s_data_bit_width_t bit_width = (i2s_data_bit_width_t)bit_depth;
+
+    i2s_chan_config_t chan_cfg = I2S_CHANNEL_DEFAULT_CONFIG(I2S_NUM_AUTO, I2S_ROLE_MASTER);
+    esp_err_t err = i2s_new_channel(&chan_cfg, NULL, &self->rx_chan);
+    if (err == ESP_ERR_NOT_FOUND) {
+        mp_raise_RuntimeError(MP_ERROR_TEXT("Peripheral in use"));
+    }
+    CHECK_ESP_RESULT(err);
+
+    // Always configure the bus as stereo. The newer-family I2S peripherals
+    // (S2/S3/C-series) ignore I2S_SLOT_MODE_MONO on RX and write both slots
+    // into the DMA buffer regardless, which yields buffers that fill at 2x
+    // the WS rate and produces half-speed audio. By configuring stereo and
+    // dropping one slot ourselves in record_to_buffer, behavior is uniform
+    // across chips.
+    i2s_std_slot_config_t slot_cfg = left_justified
+        ? (i2s_std_slot_config_t)I2S_STD_MSB_SLOT_DEFAULT_CONFIG(bit_width, I2S_SLOT_MODE_STEREO)
+        : (i2s_std_slot_config_t)I2S_STD_PHILIPS_SLOT_DEFAULT_CONFIG(bit_width, I2S_SLOT_MODE_STEREO);
+
+    i2s_std_config_t std_cfg = {
+        .clk_cfg = I2S_STD_CLK_DEFAULT_CONFIG(sample_rate),
+        .slot_cfg = slot_cfg,
+        .gpio_cfg = {
+            .mclk = main_clock != NULL ? main_clock->number : I2S_GPIO_UNUSED,
+            .bclk = bit_clock->number,
+            .ws = word_select->number,
+            .dout = I2S_GPIO_UNUSED,
+            .din = data->number,
+        },
+    };
+    CHECK_ESP_RESULT(i2s_channel_init_std_mode(self->rx_chan, &std_cfg));
+    CHECK_ESP_RESULT(i2s_channel_enable(self->rx_chan));
+
+    self->bit_clock = bit_clock;
+    self->word_select = word_select;
+    self->data = data;
+    self->mclk = main_clock;
+    self->sample_rate = sample_rate;
+    self->bit_depth = bit_depth;
+    self->output_bit_depth = output_bit_depth;
+    self->mono = mono;
+    self->samples_signed = samples_signed;
+
+    claim_pin(bit_clock);
+    claim_pin(word_select);
+    claim_pin(data);
+    if (main_clock) {
+        claim_pin(main_clock);
+    }
+}
+
+bool common_hal_audioi2sin_i2sin_deinited(audioi2sin_i2sin_obj_t *self) {
+    return self->data == NULL;
+}
+
+void common_hal_audioi2sin_i2sin_deinit(audioi2sin_i2sin_obj_t *self) {
+    if (common_hal_audioi2sin_i2sin_deinited(self)) {
+        return;
+    }
+
+    if (self->rx_chan) {
+        i2s_channel_disable(self->rx_chan);
+        i2s_del_channel(self->rx_chan);
+        self->rx_chan = NULL;
+    }
+
+    if (self->bit_clock) {
+        reset_pin_number(self->bit_clock->number);
+    }
+    self->bit_clock = NULL;
+
+    if (self->word_select) {
+        reset_pin_number(self->word_select->number);
+    }
+    self->word_select = NULL;
+
+    if (self->data) {
+        reset_pin_number(self->data->number);
+    }
+    self->data = NULL;
+
+    if (self->mclk) {
+        reset_pin_number(self->mclk->number);
+    }
+    self->mclk = NULL;
+}
+
+// Sign-extend a raw I2S sample (in the low `in_depth` bits of `raw`) to a
+// canonical int32 value.
+static inline int32_t i2sin_normalize_signed(uint32_t raw, uint8_t in_depth) {
+    if (in_depth == 32) {
+        return (int32_t)raw;
+    }
+    if (in_depth == 24) {
+        uint32_t sign_bit = 0x800000u;
+        return (int32_t)((raw ^ sign_bit) - sign_bit);
+    }
+    if (in_depth == 16) {
+        return (int16_t)(raw & 0xffffu);
+    }
+    return (int8_t)(raw & 0xffu);
+}
+
+// Read a single sample from the DMA scratch at the given byte offset for the
+// configured input bit depth.
+static inline uint32_t i2sin_read_raw(const uint8_t *src, uint8_t in_depth) {
+    if (in_depth == 8) {
+        return (uint32_t)(*src);
+    }
+    if (in_depth == 16) {
+        uint16_t v;
+        memcpy(&v, src, sizeof(v));
+        return v;
+    }
+    uint32_t v;
+    memcpy(&v, src, sizeof(v));
+    return v;
+}
+
+// Convert `raw` from `in_depth` to `out_depth` (shift-only semantics, sign-
+// preserving for signed) and write it to `buffer` at sample index `idx`.
+// Output element size: 1 byte at 8, 2 bytes at 16, 4 bytes at 24 or 32.
+static inline void i2sin_write_converted(void *buffer, uint32_t idx,
+    uint32_t raw, uint8_t in_depth, uint8_t out_depth, bool samples_signed) {
+    int32_t s = i2sin_normalize_signed(raw, in_depth);
+    int32_t shifted;
+    if (out_depth >= in_depth) {
+        shifted = (int32_t)((uint32_t)s << (out_depth - in_depth));
+    } else {
+        shifted = s >> (in_depth - out_depth);
+    }
+    uint32_t u = (uint32_t)shifted;
+    if (!samples_signed) {
+        if (out_depth >= 32) {
+            u ^= 0x80000000u;
+        } else {
+            uint32_t mask = (1u << out_depth) - 1u;
+            u = (u & mask) ^ (1u << (out_depth - 1));
+        }
+    }
+    switch (out_depth) {
+        case 8:
+            ((uint8_t *)buffer)[idx] = (uint8_t)(u & 0xffu);
+            break;
+        case 16:
+            ((uint16_t *)buffer)[idx] = (uint16_t)(u & 0xffffu);
+            break;
+        default: // 24 or 32
+            ((uint32_t *)buffer)[idx] = u;
+            break;
+    }
+}
+
+// I2S delivers signed PCM. When samples_signed is false, XOR each sample with
+// the sign bit for its width to convert to unsigned PCM (WAV convention).
+static void i2sin_convert_to_unsigned(void *buffer, uint32_t samples,
+    uint8_t bit_depth, size_t element_size) {
+    (void)element_size;
+    uint32_t *p = (uint32_t *)buffer;
+
+    if (bit_depth == 8) {
+        // 4 samples per word
+        uint32_t words = samples / 4;
+        for (uint32_t i = 0; i < words; i++) {
+            p[i] ^= 0x80808080u;
+        }
+        // tail: 0–3 leftover bytes
+        uint8_t *tail = (uint8_t *)(p + words);
+        for (uint32_t i = 0; i < (samples & 3u); i++) {
+            tail[i] ^= 0x80u;
+        }
+    } else if (bit_depth == 16) {
+        // 2 samples per word
+        uint32_t words = samples / 2;
+        for (uint32_t i = 0; i < words; i++) {
+            p[i] ^= 0x80008000u;
+        }
+        if (samples & 1u) {
+            ((uint16_t *)(p + words))[0] ^= 0x8000u;
+        }
+    } else {
+        // 24- or 32-bit: one sample per 32-bit slot
+        uint32_t mask = (bit_depth == 24) ? 0x00800000u : 0x80000000u;
+        for (uint32_t i = 0; i < samples; i++) {
+            p[i] ^= mask;
+        }
+    }
+}
+
+
+uint32_t common_hal_audioi2sin_i2sin_record_to_buffer(audioi2sin_i2sin_obj_t *self,
+    void *buffer, uint32_t length) {
+    size_t element_size = self->bit_depth / 8;
+    // 24-bit samples occupy a 32-bit slot on the I2S bus.
+    if (self->bit_depth == 24) {
+        element_size = 4;
+    }
+
+    if (self->output_bit_depth != self->bit_depth) {
+        // Bit-depth conversion path: always read at input width into scratch,
+        // convert each sample into the user's buffer at output width.
+        const uint8_t in_depth = self->bit_depth;
+        const uint8_t out_depth = self->output_bit_depth;
+        const bool samples_signed = self->samples_signed;
+        uint8_t scratch[256];
+        const size_t in_frame_bytes = 2 * element_size;
+        const size_t scratch_frames = sizeof(scratch) / in_frame_bytes;
+        uint32_t produced = 0;
+        while (produced < length) {
+            size_t want_frames;
+            if (self->mono) {
+                want_frames = length - produced;
+            } else {
+                want_frames = (length - produced + 1) / 2;
+            }
+            if (want_frames > scratch_frames) {
+                want_frames = scratch_frames;
+            }
+            size_t got_bytes = 0;
+            esp_err_t err = i2s_channel_read(self->rx_chan, scratch,
+                want_frames * in_frame_bytes, &got_bytes, portMAX_DELAY);
+            CHECK_ESP_RESULT(err);
+            size_t got_frames = got_bytes / in_frame_bytes;
+            for (size_t i = 0; i < got_frames && produced < length; i++) {
+                const uint8_t *frame = scratch + i * in_frame_bytes;
+                uint32_t left_raw = i2sin_read_raw(frame, in_depth);
+                i2sin_write_converted(buffer, produced++, left_raw,
+                    in_depth, out_depth, samples_signed);
+                if (!self->mono && produced < length) {
+                    uint32_t right_raw = i2sin_read_raw(frame + element_size, in_depth);
+                    i2sin_write_converted(buffer, produced++, right_raw,
+                        in_depth, out_depth, samples_signed);
+                }
+            }
+            if (got_frames < want_frames) {
+                break;
+            }
+        }
+        return produced;
+    }
+
+    uint32_t produced;
+    if (!self->mono) {
+        size_t result = 0;
+        esp_err_t err = i2s_channel_read(self->rx_chan, buffer, length * element_size,
+            &result, portMAX_DELAY);
+        CHECK_ESP_RESULT(err);
+        produced = result / element_size;
+    } else {
+        // Mono: bus is configured stereo, so each WS frame yields two slots in
+        // the DMA buffer. Read in chunks into a scratch and keep only the left
+        // slot of each frame.
+        uint8_t scratch[256];
+        const size_t frame_bytes = 2 * element_size;
+        const size_t scratch_frames = sizeof(scratch) / frame_bytes;
+        uint8_t *out = (uint8_t *)buffer;
+        produced = 0;
+        while (produced < length) {
+            size_t want_frames = length - produced;
+            if (want_frames > scratch_frames) {
+                want_frames = scratch_frames;
+            }
+            size_t got_bytes = 0;
+            esp_err_t err = i2s_channel_read(self->rx_chan, scratch,
+                want_frames * frame_bytes, &got_bytes, portMAX_DELAY);
+            CHECK_ESP_RESULT(err);
+            size_t got_frames = got_bytes / frame_bytes;
+            for (size_t i = 0; i < got_frames; i++) {
+                memcpy(out + produced * element_size,
+                    scratch + i * frame_bytes,
+                    element_size);
+                produced++;
+            }
+            if (got_frames < want_frames) {
+                break;
+            }
+        }
+    }
+
+    if (!self->samples_signed && produced > 0) {
+        i2sin_convert_to_unsigned(buffer, produced, self->bit_depth, element_size);
+    }
+    return produced;
+}
+
+uint8_t common_hal_audioi2sin_i2sin_get_bit_depth(audioi2sin_i2sin_obj_t *self) {
+    return self->bit_depth;
+}
+
+uint8_t common_hal_audioi2sin_i2sin_get_output_bit_depth(audioi2sin_i2sin_obj_t *self) {
+    return self->output_bit_depth;
+}
+
+uint32_t common_hal_audioi2sin_i2sin_get_sample_rate(audioi2sin_i2sin_obj_t *self) {
+    return self->sample_rate;
+}
+
+bool common_hal_audioi2sin_i2sin_get_samples_signed(audioi2sin_i2sin_obj_t *self) {
+    return self->samples_signed;
+}
+
+#endif // CIRCUITPY_AUDIOI2SIN
diff --git a/ports/espressif/common-hal/audioi2sin/I2SIn.h b/ports/espressif/common-hal/audioi2sin/I2SIn.h
new file mode 100644
index 0000000000000..05b533ac89d85
--- /dev/null
+++ b/ports/espressif/common-hal/audioi2sin/I2SIn.h
@@ -0,0 +1,31 @@
+// This file is part of the CircuitPython project: https://circuitpython.org
+//
+// SPDX-FileCopyrightText: Copyright (c) 2026 Tim Cocks for Adafruit Industries
+//
+// SPDX-License-Identifier: MIT
+
+#pragma once
+
+#include "py/obj.h"
+
+#include "common-hal/microcontroller/Pin.h"
+
+#include "driver/i2s_std.h"
+
+#if CIRCUITPY_AUDIOI2SIN
+
+typedef struct {
+    mp_obj_base_t base;
+    i2s_chan_handle_t rx_chan;
+    const mcu_pin_obj_t *bit_clock;
+    const mcu_pin_obj_t *word_select;
+    const mcu_pin_obj_t *data;
+    const mcu_pin_obj_t *mclk;
+    uint32_t sample_rate;
+    uint8_t bit_depth;
+    uint8_t output_bit_depth;
+    bool mono;
+    bool samples_signed;
+} audioi2sin_i2sin_obj_t;
+
+#endif
diff --git a/ports/espressif/common-hal/audioi2sin/__init__.c b/ports/espressif/common-hal/audioi2sin/__init__.c
new file mode 100644
index 0000000000000..584c821b99631
--- /dev/null
+++ b/ports/espressif/common-hal/audioi2sin/__init__.c
@@ -0,0 +1,5 @@
+// This file is part of the CircuitPython project: https://circuitpython.org
+//
+// SPDX-FileCopyrightText: Copyright (c) 2026 Tim Cocks for Adafruit Industries
+//
+// SPDX-License-Identifier: MIT
diff --git a/ports/espressif/mpconfigport.mk b/ports/espressif/mpconfigport.mk
index 67f8ca2987bd8..cc8e29cecca0f 100644
--- a/ports/espressif/mpconfigport.mk
+++ b/ports/espressif/mpconfigport.mk
@@ -68,6 +68,7 @@ CIRCUITPY_ALARM_TOUCH ?= 0
 CIRCUITPY_ANALOGBUFIO ?= 1
 CIRCUITPY_AUDIOBUSIO ?= 1
 CIRCUITPY_AUDIOBUSIO_PDMIN ?= 0
+CIRCUITPY_AUDIOI2SIN ?= 1
 CIRCUITPY_AUDIOIO ?= 1
 CIRCUITPY_BLEIO_HCI = 0
 CIRCUITPY_BLEIO_NATIVE ?= 1
@@ -132,6 +133,7 @@ CIRCUITPY_ANALOGBUFIO = 0
 
 # No I2S
 CIRCUITPY_AUDIOBUSIO = 0
+CIRCUITPY_AUDIOI2SIN = 0
 
 # No DAC
 CIRCUITPY_AUDIOIO = 0
diff --git a/ports/raspberrypi/bindings/rp2pio/StateMachine.h b/ports/raspberrypi/bindings/rp2pio/StateMachine.h
index 16f884bcfca32..3c775a96449f0 100644
--- a/ports/raspberrypi/bindings/rp2pio/StateMachine.h
+++ b/ports/raspberrypi/bindings/rp2pio/StateMachine.h
@@ -62,6 +62,18 @@ bool common_hal_rp2pio_statemachine_background_read(rp2pio_statemachine_obj_t *s
 bool common_hal_rp2pio_statemachine_stop_background_write(rp2pio_statemachine_obj_t *self);
 bool common_hal_rp2pio_statemachine_stop_background_read(rp2pio_statemachine_obj_t *self);
 
+// Set the once / loop / loop2 read buffers from raw pointers without going
+// through an mp_obj_t wrapper. Pass NULL/0 for unused slots. The caller owns
+// the memory; it must remain valid until stop_background_read.
+void common_hal_rp2pio_statemachine_set_read_buffers_raw(rp2pio_statemachine_obj_t *self,
+    void *once, size_t once_len,
+    void *loop, size_t loop_len,
+    void *loop2, size_t loop2_len);
+
+// Returns the DMA channel index used by the current background read, or -1
+// if no background read is active.
+int common_hal_rp2pio_statemachine_get_read_dma_channel(rp2pio_statemachine_obj_t *self);
+
 mp_int_t common_hal_rp2pio_statemachine_get_pending_write(rp2pio_statemachine_obj_t *self);
 mp_int_t common_hal_rp2pio_statemachine_get_pending_read(rp2pio_statemachine_obj_t *self);
 
diff --git a/ports/raspberrypi/common-hal/audioi2sin/I2SIn.c b/ports/raspberrypi/common-hal/audioi2sin/I2SIn.c
new file mode 100644
index 0000000000000..0de4fe69b8cbc
--- /dev/null
+++ b/ports/raspberrypi/common-hal/audioi2sin/I2SIn.c
@@ -0,0 +1,563 @@
+// This file is part of the CircuitPython project: https://circuitpython.org
+//
+// SPDX-FileCopyrightText: Copyright (c) 2026 Tim Cocks for Adafruit Industries
+//
+// SPDX-License-Identifier: MIT
+
+#include <stdint.h>
+#include <string.h>
+
+#include "py/mperrno.h"
+#include "py/mphal.h"
+#include "py/runtime.h"
+#include "shared/runtime/interrupt_char.h"
+#include "common-hal/audioi2sin/I2SIn.h"
+#include "shared-bindings/audioi2sin/I2SIn.h"
+#include "shared-bindings/microcontroller/Pin.h"
+#include "bindings/rp2pio/StateMachine.h"
+#include "supervisor/port.h"
+
+#include "hardware/dma.h"
+
+#if CIRCUITPY_AUDIOI2SIN
+
+// 16-bit programs sample a stereo frame of 16+16 = 32 bits and rely on
+// auto-push at 32 to deliver one packed (right<<16 | left) word per frame.
+// 32-bit programs sample 32 bits per channel and produce two FIFO words per
+// frame (right first, then left). Each bit takes 6 PIO clocks (a [2]-delay
+// pair). 24-bit recordings reuse the 32-bit programs because most 24-bit
+// MEMS mics (SPH0645LM4H, INMP441, ICS-43434) transmit their 24 valid bits
+// left-justified inside a 32-bit slot.
+//
+// `in pins 1` runs on a cycle where side-set drives BCLK high. The slave
+// updates the data line on the BCLK falling edge, so by the rising edge it
+// has settled and is safe to sample. Sampling at BCLK low (the previous,
+// incorrect arrangement) catches the data mid-transition and the result is
+// effectively noise.
+#define PIO_CLOCKS_PER_BIT (6)
+
+// Master-mode RX, regular pin order (BCLK = WS - 1), Philips alignment.
+static const uint16_t i2sin_program[] = {
+    //     .wrap_target
+    0xf04e, //  0: set    y, 14           side 2
+    0x5a01, //  1: in     pins, 1         side 3 [2]
+    0x1281, //  2: jmp    y--, 1          side 2 [2]
+    0x4a01, //  3: in     pins, 1         side 1 [2]
+    0xe24e, //  4: set    y, 14           side 0 [2]
+    0x4a01, //  5: in     pins, 1         side 1 [2]
+    0x0285, //  6: jmp    y--, 5          side 0 [2]
+    0x5a01, //  7: in     pins, 1         side 3 [2]
+            //     .wrap
+};
+
+// Master-mode RX, regular pin order, left-justified.
+static const uint16_t i2sin_program_left_justified[] = {
+    //     .wrap_target
+    0xe04e, //  0: set    y, 14           side 0
+    0x5a01, //  1: in     pins, 1         side 3 [2]
+    0x1281, //  2: jmp    y--, 1          side 2 [2]
+    0x5a01, //  3: in     pins, 1         side 3 [2]
+    0xf24e, //  4: set    y, 14           side 2 [2]
+    0x4a01, //  5: in     pins, 1         side 1 [2]
+    0x0285, //  6: jmp    y--, 5          side 0 [2]
+    0x4a01, //  7: in     pins, 1         side 1 [2]
+            //     .wrap
+};
+
+// Master-mode RX, swapped pin order (BCLK = WS + 1), Philips alignment.
+static const uint16_t i2sin_program_swap[] = {
+    //     .wrap_target
+    0xe84e, //  0: set    y, 14           side 1
+    0x5a01, //  1: in     pins, 1         side 3 [2]
+    0x0a81, //  2: jmp    y--, 1          side 1 [2]
+    0x5201, //  3: in     pins, 1         side 2 [2]
+    0xe24e, //  4: set    y, 14           side 0 [2]
+    0x5201, //  5: in     pins, 1         side 2 [2]
+    0x0285, //  6: jmp    y--, 5          side 0 [2]
+    0x5a01, //  7: in     pins, 1         side 3 [2]
+            //     .wrap
+};
+
+// Master-mode RX, swapped pin order, left-justified.
+static const uint16_t i2sin_program_left_justified_swap[] = {
+    //     .wrap_target
+    0xe04e, //  0: set    y, 14           side 0
+    0x5a01, //  1: in     pins, 1         side 3 [2]
+    0x0a81, //  2: jmp    y--, 1          side 1 [2]
+    0x5a01, //  3: in     pins, 1         side 3 [2]
+    0xea4e, //  4: set    y, 14           side 1 [2]
+    0x5201, //  5: in     pins, 1         side 2 [2]
+    0x0285, //  6: jmp    y--, 5          side 0 [2]
+    0x5201, //  7: in     pins, 1         side 2 [2]
+            //     .wrap
+};
+
+// 32-bit-per-channel variants: identical to the 16-bit programs above except
+// the loop counter is set to 30 (so each `bitloop` runs 31 in's, plus one
+// outside the loop = 32 in's per channel).
+static const uint16_t i2sin_program_32[] = {
+    //     .wrap_target
+    0xf05e, //  0: set    y, 30           side 2
+    0x5a01, //  1: in     pins, 1         side 3 [2]
+    0x1281, //  2: jmp    y--, 1          side 2 [2]
+    0x4a01, //  3: in     pins, 1         side 1 [2]
+    0xe25e, //  4: set    y, 30           side 0 [2]
+    0x4a01, //  5: in     pins, 1         side 1 [2]
+    0x0285, //  6: jmp    y--, 5          side 0 [2]
+    0x5a01, //  7: in     pins, 1         side 3 [2]
+            //     .wrap
+};
+
+static const uint16_t i2sin_program_left_justified_32[] = {
+    //     .wrap_target
+    0xe05e, //  0: set    y, 30           side 0
+    0x5a01, //  1: in     pins, 1         side 3 [2]
+    0x1281, //  2: jmp    y--, 1          side 2 [2]
+    0x5a01, //  3: in     pins, 1         side 3 [2]
+    0xf25e, //  4: set    y, 30           side 2 [2]
+    0x4a01, //  5: in     pins, 1         side 1 [2]
+    0x0285, //  6: jmp    y--, 5          side 0 [2]
+    0x4a01, //  7: in     pins, 1         side 1 [2]
+            //     .wrap
+};
+
+static const uint16_t i2sin_program_swap_32[] = {
+    //     .wrap_target
+    0xe85e, //  0: set    y, 30           side 1
+    0x5a01, //  1: in     pins, 1         side 3 [2]
+    0x0a81, //  2: jmp    y--, 1          side 1 [2]
+    0x5201, //  3: in     pins, 1         side 2 [2]
+    0xe25e, //  4: set    y, 30           side 0 [2]
+    0x5201, //  5: in     pins, 1         side 2 [2]
+    0x0285, //  6: jmp    y--, 5          side 0 [2]
+    0x5a01, //  7: in     pins, 1         side 3 [2]
+            //     .wrap
+};
+
+static const uint16_t i2sin_program_left_justified_swap_32[] = {
+    //     .wrap_target
+    0xe05e, //  0: set    y, 30           side 0
+    0x5a01, //  1: in     pins, 1         side 3 [2]
+    0x0a81, //  2: jmp    y--, 1          side 1 [2]
+    0x5a01, //  3: in     pins, 1         side 3 [2]
+    0xea5e, //  4: set    y, 30           side 1 [2]
+    0x5201, //  5: in     pins, 1         side 2 [2]
+    0x0285, //  6: jmp    y--, 5          side 0 [2]
+    0x5201, //  7: in     pins, 1         side 2 [2]
+            //     .wrap
+};
+
+// Caller validates that pins are free.
+void common_hal_audioi2sin_i2sin_construct(audioi2sin_i2sin_obj_t *self,
+    const mcu_pin_obj_t *bit_clock, const mcu_pin_obj_t *word_select,
+    const mcu_pin_obj_t *data, const mcu_pin_obj_t *main_clock,
+    uint32_t sample_rate, uint8_t bit_depth, uint8_t output_bit_depth,
+    bool mono, bool left_justified, bool samples_signed) {
+
+    if (main_clock != NULL) {
+        mp_raise_NotImplementedError_varg(MP_ERROR_TEXT("%q"), MP_QSTR_main_clock);
+    }
+    if (bit_depth != 16 && bit_depth != 24 && bit_depth != 32) {
+        mp_raise_ValueError_varg(MP_ERROR_TEXT("%q must be 16, 24, or 32"), MP_QSTR_bit_depth);
+    }
+
+    // 24- and 32-bit recordings both clock 32 bits per channel; 24-bit MEMS
+    // mics deliver their data left-justified inside that 32-bit slot.
+    bool wide = (bit_depth != 16);
+    uint32_t bits_per_channel = wide ? 32 : 16;
+    uint32_t pio_clocks_per_frame = bits_per_channel * 2 * PIO_CLOCKS_PER_BIT;
+
+    const mcu_pin_obj_t *sideset_pin = NULL;
+    const uint16_t *program = NULL;
+    size_t program_len = 0;
+
+    if (bit_clock->number == word_select->number - 1) {
+        sideset_pin = bit_clock;
+        if (left_justified) {
+            program = wide ? i2sin_program_left_justified_32 : i2sin_program_left_justified;
+            program_len = wide ? MP_ARRAY_SIZE(i2sin_program_left_justified_32)
+                               : MP_ARRAY_SIZE(i2sin_program_left_justified);
+        } else {
+            program = wide ? i2sin_program_32 : i2sin_program;
+            program_len = wide ? MP_ARRAY_SIZE(i2sin_program_32)
+                               : MP_ARRAY_SIZE(i2sin_program);
+        }
+    } else if (bit_clock->number == word_select->number + 1) {
+        sideset_pin = word_select;
+        if (left_justified) {
+            program = wide ? i2sin_program_left_justified_swap_32 : i2sin_program_left_justified_swap;
+            program_len = wide ? MP_ARRAY_SIZE(i2sin_program_left_justified_swap_32)
+                               : MP_ARRAY_SIZE(i2sin_program_left_justified_swap);
+        } else {
+            program = wide ? i2sin_program_swap_32 : i2sin_program_swap;
+            program_len = wide ? MP_ARRAY_SIZE(i2sin_program_swap_32)
+                               : MP_ARRAY_SIZE(i2sin_program_swap);
+        }
+    } else {
+        mp_raise_ValueError(MP_ERROR_TEXT("Bit clock and word select must be sequential GPIO pins"));
+    }
+
+    common_hal_rp2pio_statemachine_construct(
+        &self->state_machine,
+        program, program_len,
+        sample_rate * pio_clocks_per_frame,
+        NULL, 0, // init
+        NULL, 0, // may_exec
+        NULL, 0, PIO_PINMASK32_NONE, PIO_PINMASK32_NONE, // out pin
+        data, 1, // in pins
+        PIO_PINMASK32_NONE, PIO_PINMASK32_NONE, // in pulls
+        NULL, 0, PIO_PINMASK32_NONE, PIO_PINMASK32_FROM_VALUE(0x1f), // set pins
+        sideset_pin, 2, false, PIO_PINMASK32_NONE, PIO_PINMASK32_FROM_VALUE(0x1f), // sideset pins
+        false, // No sideset enable
+        NULL, PULL_NONE, // jump pin
+        PIO_PINMASK_NONE, // wait gpio pins
+        true, // exclusive pin use
+        false, 32, false, // out settings (unused)
+        false, // Wait for txstall
+        true, 32, false, // in settings: auto-push at 32 bits, shift left (MSB first)
+        false, // Not user-interruptible.
+        0, -1, // wrap settings
+        PIO_ANY_OFFSET,
+        PIO_FIFO_TYPE_DEFAULT,
+        PIO_MOV_STATUS_DEFAULT,
+        PIO_MOV_N_DEFAULT);
+
+    uint32_t actual_frequency = common_hal_rp2pio_statemachine_get_frequency(&self->state_machine);
+    self->sample_rate = actual_frequency / pio_clocks_per_frame;
+    self->bit_depth = bit_depth;
+    self->output_bit_depth = output_bit_depth;
+    self->mono = mono;
+    self->samples_signed = samples_signed;
+    self->left_justified = left_justified;
+    self->settled = false;
+    self->ring = NULL;
+    self->ring_size = 0;
+    self->half_size = 0;
+    self->read_pos = 0;
+    self->dma_channel = -1;
+    self->overflow = false;
+
+    // Each PIO frame produces 4 bytes in the FIFO regardless of bit depth
+    // (16-bit auto-pushes one packed stereo word, 24/32-bit pushes two
+    // separate 32-bit words). One stereo frame is therefore either 4 or
+    // 8 bytes; size the half-buffer for ~40 ms of audio so a slow consumer
+    // (SD card flush etc.) can complete without overrunning.
+    size_t bytes_per_frame = (bit_depth == 16) ? 4 : 8;
+    size_t target = (size_t)self->sample_rate * bytes_per_frame * 40 / 1000;
+    size_t half_size = (target > 4096) ? target : 4096;
+    // Round up to a multiple of 8 so 24/32-bit pair reads never straddle
+    // the half boundary.
+    half_size = (half_size + 7u) & ~(size_t)7u;
+
+    self->ring = (uint8_t *)port_malloc(2 * half_size, true);
+    if (self->ring == NULL) {
+        common_hal_rp2pio_statemachine_deinit(&self->state_machine);
+        m_malloc_fail(2 * half_size);
+    }
+    self->half_size = half_size;
+    self->ring_size = 2 * half_size;
+
+    common_hal_rp2pio_statemachine_set_read_buffers_raw(&self->state_machine,
+        NULL, 0,
+        self->ring, half_size,
+        self->ring + half_size, half_size);
+    if (!common_hal_rp2pio_statemachine_background_read(&self->state_machine, 4, false)) {
+        port_free(self->ring);
+        self->ring = NULL;
+        common_hal_rp2pio_statemachine_deinit(&self->state_machine);
+        mp_raise_OSError(MP_EIO);
+    }
+    self->dma_channel = common_hal_rp2pio_statemachine_get_read_dma_channel(&self->state_machine);
+}
+
+bool common_hal_audioi2sin_i2sin_deinited(audioi2sin_i2sin_obj_t *self) {
+    return common_hal_rp2pio_statemachine_deinited(&self->state_machine);
+}
+
+void common_hal_audioi2sin_i2sin_deinit(audioi2sin_i2sin_obj_t *self) {
+    if (common_hal_audioi2sin_i2sin_deinited(self)) {
+        return;
+    }
+    common_hal_rp2pio_statemachine_stop_background_read(&self->state_machine);
+    common_hal_rp2pio_statemachine_deinit(&self->state_machine);
+    if (self->ring != NULL) {
+        port_free(self->ring);
+        self->ring = NULL;
+    }
+    self->ring_size = 0;
+    self->half_size = 0;
+    self->dma_channel = -1;
+}
+
+uint8_t common_hal_audioi2sin_i2sin_get_bit_depth(audioi2sin_i2sin_obj_t *self) {
+    return self->bit_depth;
+}
+
+uint8_t common_hal_audioi2sin_i2sin_get_output_bit_depth(audioi2sin_i2sin_obj_t *self) {
+    return self->output_bit_depth;
+}
+
+uint32_t common_hal_audioi2sin_i2sin_get_sample_rate(audioi2sin_i2sin_obj_t *self) {
+    return self->sample_rate;
+}
+
+bool common_hal_audioi2sin_i2sin_get_samples_signed(audioi2sin_i2sin_obj_t *self) {
+    return self->samples_signed;
+}
+
+// In 16-bit mode, each PIO frame produces a single 32-bit FIFO word with bits
+// 31..16 = right channel and bits 15..0 = left channel (both MSB-first signed
+// 16-bit). In 24/32-bit mode each frame produces two FIFO words: right first,
+// then left, each MSB-first in the full 32 bits. For mono we keep the left
+// channel; for stereo we emit (left, right) pairs.
+//
+// `output_buffer_length` is the requested number of samples to write (sample
+// width = 2 bytes for bit_depth=16, 4 bytes for bit_depth=24 or 32). Returns
+// the number actually written.
+// Compute the byte offset inside `ring` that the DMA is currently writing
+// (one past the last word it finished). Always lies in [0, ring_size).
+static size_t i2sin_write_pos(audioi2sin_i2sin_obj_t *self) {
+    uintptr_t addr = (uintptr_t)dma_channel_hw_addr(self->dma_channel)->write_addr;
+    uintptr_t base = (uintptr_t)self->ring;
+    if (addr < base || addr >= base + self->ring_size) {
+        // The ISR retargets write_addr to the start of the next half right
+        // after a transfer completes; it should always be in-range, but if
+        // we observe it mid-update just report "no new data".
+        return self->read_pos;
+    }
+    return (size_t)(addr - base);
+}
+
+// 24-bit non-left-justified data arrives in the low 24 bits of the FIFO word
+// with the sign bit at bit 23 and bits 31..24 zero. To make it decode
+// correctly as int32 (array typecode "i"), lift the sign bit to bit 31.
+static inline uint32_t movesign24(uint32_t val) {
+    return ((val & 0x800000u) << 8) | (val & 0x7fffffu);
+}
+
+// Sign-extend a raw FIFO sample to a canonical int32 value. `raw` holds the
+// sample as delivered by the PIO program for the given input bit depth and
+// alignment. The returned int32 represents the same magnitude with the sign
+// bit at bit 31.
+static inline int32_t i2sin_normalize_signed(uint32_t raw, uint8_t in_depth,
+    bool left_justified) {
+    if (in_depth == 32) {
+        return (int32_t)raw;
+    }
+    if (in_depth == 24) {
+        if (left_justified) {
+            // value in bits 31..8, sign at 31; arithmetic shift right 8
+            return (int32_t)raw >> 8;
+        }
+        // value in bits 23..0, sign at 23
+        uint32_t sign_bit = 0x800000u;
+        return (int32_t)((raw ^ sign_bit) - sign_bit);
+    }
+    // 16-bit: low 16 bits, sign at 15
+    return (int16_t)(raw & 0xffffu);
+}
+
+// Write `raw` (input-depth bits, just-read FIFO sample) to `buffer` at sample
+// index `idx`, converting from `in_depth` to `out_depth` and (if needed)
+// flipping the sign bit for the unsigned-WAV convention. Output element size
+// follows `out_depth`: 1 byte at 8, 2 bytes at 16, 4 bytes at 24 or 32.
+//
+// For signed 24-bit output, the int32 slot holds the sign-extended value
+// (range -2^23 .. 2^23-1) — unlike the default `output_bit_depth=bit_depth=24`
+// path which uses `movesign24`, the converted path returns proper two's
+// complement so the result decodes correctly as int32.
+static inline void i2sin_write_converted(void *buffer, uint32_t idx,
+    uint32_t raw, uint8_t in_depth, uint8_t out_depth,
+    bool samples_signed, bool left_justified) {
+    int32_t s = i2sin_normalize_signed(raw, in_depth, left_justified);
+    int32_t shifted;
+    if (out_depth >= in_depth) {
+        shifted = (int32_t)((uint32_t)s << (out_depth - in_depth));
+    } else {
+        shifted = s >> (in_depth - out_depth);
+    }
+    uint32_t u = (uint32_t)shifted;
+    if (!samples_signed) {
+        if (out_depth >= 32) {
+            u ^= 0x80000000u;
+        } else {
+            uint32_t mask = (1u << out_depth) - 1u;
+            u = (u & mask) ^ (1u << (out_depth - 1));
+        }
+    }
+    switch (out_depth) {
+        case 8:
+            ((uint8_t *)buffer)[idx] = (uint8_t)(u & 0xffu);
+            break;
+        case 16:
+            ((uint16_t *)buffer)[idx] = (uint16_t)(u & 0xffffu);
+            break;
+        default: // 24 or 32
+            ((uint32_t *)buffer)[idx] = u;
+            break;
+    }
+}
+
+uint32_t common_hal_audioi2sin_i2sin_record_to_buffer(audioi2sin_i2sin_obj_t *self,
+    void *buffer, uint32_t output_buffer_length) {
+    uint32_t output_count = 0;
+    const size_t ring_size = self->ring_size;
+    const size_t half_size = self->half_size;
+
+    // I2S delivers signed PCM. When the caller asked for unsigned samples,
+    // flip the sign bit per sample (XOR with 0x8000 for 16-bit, 0x800000 for
+    // 24-bit data in a 32-bit slot, 0x80000000 for 32-bit), matching the WAV
+    // convention. The default (no-conversion) path applies the flip to the
+    // raw FIFO word before splitting into channels; the conversion path
+    // applies the flip per output sample at output bit width.
+    const bool convert = self->output_bit_depth != self->bit_depth;
+    const uint32_t flip16 = (!convert && !self->samples_signed) ? 0x80008000u : 0u;
+    const uint32_t flip32 = (!convert && !self->samples_signed)
+        ? (self->bit_depth == 24 ? 0x800000u : 0x80000000u)
+        : 0u;
+    const bool fix_sign24 = !convert
+        && self->bit_depth == 24
+        && self->samples_signed
+        && !self->left_justified;
+    const uint8_t in_depth = self->bit_depth;
+    const uint8_t out_depth = self->output_bit_depth;
+    const bool left_justified = self->left_justified;
+    const bool samples_signed = self->samples_signed;
+
+    if (self->bit_depth == 16) {
+        // 16-bit mode auto-pushes one stereo frame per FIFO word. The DMA has
+        // been streaming since construct time, so the ring already contains
+        // settled data; drop the first 4 bytes once to discard a single
+        // pre-record frame (matches the prior synchronous behaviour).
+        uint16_t *output = convert ? NULL : (uint16_t *)buffer;
+        while (output_count < output_buffer_length) {
+            size_t write_pos = i2sin_write_pos(self);
+            size_t avail = (write_pos + ring_size - self->read_pos) % ring_size;
+            if (avail > half_size) {
+                // DMA has filled more than one half ahead of us -- we lost
+                // data. Snap to just behind the DMA on a 4-byte boundary.
+                self->overflow = true;
+                self->read_pos = write_pos & ~(size_t)3u;
+                avail = 0;
+            }
+            if (!self->settled && avail >= 4) {
+                self->read_pos = (self->read_pos + 4) % ring_size;
+                avail -= 4;
+                self->settled = true;
+            }
+            if (avail < 4) {
+                RUN_BACKGROUND_TASKS;
+                if (mp_hal_is_interrupted()) {
+                    return output_count;
+                }
+                continue;
+            }
+            while (avail >= 4 && output_count < output_buffer_length) {
+                uint32_t frame = *(volatile uint32_t *)(self->ring + self->read_pos) ^ flip16;
+                uint16_t left = (uint16_t)(frame & 0xffff);
+                uint16_t right = (uint16_t)(frame >> 16);
+                if (!convert) {
+                    if (self->mono) {
+                        output[output_count++] = left;
+                    } else {
+                        output[output_count++] = left;
+                        if (output_count >= output_buffer_length) {
+                            self->read_pos = (self->read_pos + 4) % ring_size;
+                            avail -= 4;
+                            break;
+                        }
+                        output[output_count++] = right;
+                    }
+                } else {
+                    i2sin_write_converted(buffer, output_count++, left,
+                        in_depth, out_depth, samples_signed, left_justified);
+                    if (!self->mono) {
+                        if (output_count >= output_buffer_length) {
+                            self->read_pos = (self->read_pos + 4) % ring_size;
+                            avail -= 4;
+                            break;
+                        }
+                        i2sin_write_converted(buffer, output_count++, right,
+                            in_depth, out_depth, samples_signed, left_justified);
+                    }
+                }
+                self->read_pos = (self->read_pos + 4) % ring_size;
+                avail -= 4;
+            }
+        }
+    } else {
+        // 24-/32-bit mode emits two FIFO pushes per stereo frame (right then
+        // left). The state machine was started at instruction 0 by the
+        // constructor, so the very first push is the right channel and
+        // alternation is preserved as long as we never touch the program
+        // counter and always read an even number of words. half_size is a
+        // multiple of 8, so reading 8-byte pairs stays aligned across the
+        // ring wrap.
+        uint32_t *output = convert ? NULL : (uint32_t *)buffer;
+        while (output_count < output_buffer_length) {
+            size_t write_pos = i2sin_write_pos(self);
+            size_t avail = (write_pos + ring_size - self->read_pos) % ring_size;
+            if (avail > half_size) {
+                // Overflow: snap to a frame-aligned position one half behind
+                // the DMA's current half so we resume on the right channel.
+                self->overflow = true;
+                size_t cur_half = (write_pos < half_size) ? 0 : half_size;
+                self->read_pos = (cur_half + half_size) % ring_size;
+                self->settled = false;
+                avail = (write_pos + ring_size - self->read_pos) % ring_size;
+            }
+            if (!self->settled && avail >= 8) {
+                self->read_pos = (self->read_pos + 8) % ring_size;
+                avail -= 8;
+                self->settled = true;
+            }
+            if (avail < 8) {
+                RUN_BACKGROUND_TASKS;
+                if (mp_hal_is_interrupted()) {
+                    return output_count;
+                }
+                continue;
+            }
+            while (avail >= 8 && output_count < output_buffer_length) {
+                uint32_t right = *(volatile uint32_t *)(self->ring + self->read_pos) ^ flip32;
+                size_t next_pos = (self->read_pos + 4) % ring_size;
+                uint32_t left = *(volatile uint32_t *)(self->ring + next_pos) ^ flip32;
+                if (fix_sign24) {
+                    right = movesign24(right);
+                    left = movesign24(left);
+                }
+                if (!convert) {
+                    if (self->mono) {
+                        output[output_count++] = left;
+                    } else {
+                        output[output_count++] = left;
+                        if (output_count >= output_buffer_length) {
+                            self->read_pos = (self->read_pos + 8) % ring_size;
+                            avail -= 8;
+                            break;
+                        }
+                        output[output_count++] = right;
+                    }
+                } else {
+                    i2sin_write_converted(buffer, output_count++, left,
+                        in_depth, out_depth, samples_signed, left_justified);
+                    if (!self->mono) {
+                        if (output_count >= output_buffer_length) {
+                            self->read_pos = (self->read_pos + 8) % ring_size;
+                            avail -= 8;
+                            break;
+                        }
+                        i2sin_write_converted(buffer, output_count++, right,
+                            in_depth, out_depth, samples_signed, left_justified);
+                    }
+                }
+                self->read_pos = (self->read_pos + 8) % ring_size;
+                avail -= 8;
+            }
+        }
+    }
+
+    return output_count;
+}
+
+#endif // CIRCUITPY_AUDIOI2SIN
diff --git a/ports/raspberrypi/common-hal/audioi2sin/I2SIn.h b/ports/raspberrypi/common-hal/audioi2sin/I2SIn.h
new file mode 100644
index 0000000000000..525c72e3c5e0a
--- /dev/null
+++ b/ports/raspberrypi/common-hal/audioi2sin/I2SIn.h
@@ -0,0 +1,32 @@
+// This file is part of the CircuitPython project: https://circuitpython.org
+//
+// SPDX-FileCopyrightText: Copyright (c) 2026 Tim Cocks for Adafruit Industries
+//
+// SPDX-License-Identifier: MIT
+
+#pragma once
+
+#include "common-hal/microcontroller/Pin.h"
+#include "bindings/rp2pio/StateMachine.h"
+
+#include "py/obj.h"
+
+typedef struct {
+    mp_obj_base_t base;
+    uint32_t sample_rate;
+    uint8_t bit_depth;
+    uint8_t output_bit_depth;
+    bool mono;
+    bool samples_signed;
+    bool left_justified;
+    bool settled;
+    rp2pio_statemachine_obj_t state_machine;
+    // Background DMA ring buffer. The state machine alternates DMA writes
+    // between the two halves so BCLK never stalls between record() calls.
+    uint8_t *ring;
+    size_t ring_size;
+    size_t half_size;
+    size_t read_pos;
+    int dma_channel;
+    bool overflow;
+} audioi2sin_i2sin_obj_t;
diff --git a/ports/raspberrypi/common-hal/audioi2sin/README.pio b/ports/raspberrypi/common-hal/audioi2sin/README.pio
new file mode 100644
index 0000000000000..664c1301a7228
--- /dev/null
+++ b/ports/raspberrypi/common-hal/audioi2sin/README.pio
@@ -0,0 +1,14 @@
+.pio files right now are compiled by hand with pico-sdk/tools/pioasm and inserted into I2SIn.c
+
+i2sin.pio              I2S RX, 16 bits/channel, regular pin order, not left_justified
+i2sin_left.pio         I2S RX, 16 bits/channel, regular pin order, left_justified
+i2sin_swap.pio         I2S RX, 16 bits/channel, swapped pin order, not left_justified
+i2sin_swap_left.pio    I2S RX, 16 bits/channel, swapped pin order, left_justified
+i2sin_32.pio           I2S RX, 32 bits/channel, regular pin order, not left_justified
+i2sin_left_32.pio      I2S RX, 32 bits/channel, regular pin order, left_justified
+i2sin_swap_32.pio      I2S RX, 32 bits/channel, swapped pin order, not left_justified
+i2sin_swap_left_32.pio I2S RX, 32 bits/channel, swapped pin order, left_justified
+
+The 32-bit programs are also used for bit_depth=24 because most 24-bit I2S
+mics (SPH0645LM4H, INMP441, ICS-43434) place their 24 valid data bits
+left-justified inside a 32-bit slot.
diff --git a/ports/raspberrypi/common-hal/audioi2sin/__init__.c b/ports/raspberrypi/common-hal/audioi2sin/__init__.c
new file mode 100644
index 0000000000000..584c821b99631
--- /dev/null
+++ b/ports/raspberrypi/common-hal/audioi2sin/__init__.c
@@ -0,0 +1,5 @@
+// This file is part of the CircuitPython project: https://circuitpython.org
+//
+// SPDX-FileCopyrightText: Copyright (c) 2026 Tim Cocks for Adafruit Industries
+//
+// SPDX-License-Identifier: MIT
diff --git a/ports/raspberrypi/common-hal/audioi2sin/i2sin.pio b/ports/raspberrypi/common-hal/audioi2sin/i2sin.pio
new file mode 100644
index 0000000000000..109d1ed5ab494
--- /dev/null
+++ b/ports/raspberrypi/common-hal/audioi2sin/i2sin.pio
@@ -0,0 +1,27 @@
+; This file is part of the CircuitPython project: https://circuitpython.org
+;
+; SPDX-FileCopyrightText: Copyright (c) 2026 Tim Cocks for Adafruit Industries
+;
+; SPDX-License-Identifier: MIT
+
+.program i2sin
+.side_set 2
+
+; Master-mode I2S RX. Generates BCLK and LRCLK via side-set and samples the
+; data pin. The slave updates `data` on BCLK falling edge, so the master
+; samples on the rising edge: every `in pins 1` runs on a side-set value
+; with BCLK=1, and the loop/transition instructions hold BCLK=0 so the
+; slave has time to settle the next bit.
+                    ;        /--- LRCLK
+                    ;        |/-- BCLK
+                    ;        ||
+    set y 14          side 0b10
+bitloop1:
+    in pins 1         side 0b11 [2] ; Right channel first
+    jmp y-- bitloop1  side 0b10 [2]
+    in pins 1         side 0b01 [2]
+    set y 14          side 0b00 [2]
+bitloop0:
+    in pins 1         side 0b01 [2] ; Then left channel
+    jmp y-- bitloop0  side 0b00 [2]
+    in pins 1         side 0b11 [2]
diff --git a/ports/raspberrypi/common-hal/audioi2sin/i2sin_32.pio b/ports/raspberrypi/common-hal/audioi2sin/i2sin_32.pio
new file mode 100644
index 0000000000000..d3d7fb5aa6f52
--- /dev/null
+++ b/ports/raspberrypi/common-hal/audioi2sin/i2sin_32.pio
@@ -0,0 +1,24 @@
+; This file is part of the CircuitPython project: https://circuitpython.org
+;
+; SPDX-FileCopyrightText: Copyright (c) 2026 Tim Cocks for Adafruit Industries
+;
+; SPDX-License-Identifier: MIT
+
+.program i2sin_32
+.side_set 2
+
+; Master-mode I2S RX, 32 bits per channel (also used for 24-bit mics that
+; transmit data left-justified in a 32-bit slot).
+                    ;        /--- LRCLK
+                    ;        |/-- BCLK
+                    ;        ||
+    set y 30          side 0b10
+bitloop1:
+    in pins 1         side 0b11 [2] ; Right channel first
+    jmp y-- bitloop1  side 0b10 [2]
+    in pins 1         side 0b01 [2]
+    set y 30          side 0b00 [2]
+bitloop0:
+    in pins 1         side 0b01 [2] ; Then left channel
+    jmp y-- bitloop0  side 0b00 [2]
+    in pins 1         side 0b11 [2]
diff --git a/ports/raspberrypi/common-hal/audioi2sin/i2sin_left.pio b/ports/raspberrypi/common-hal/audioi2sin/i2sin_left.pio
new file mode 100644
index 0000000000000..eb2b42a70312e
--- /dev/null
+++ b/ports/raspberrypi/common-hal/audioi2sin/i2sin_left.pio
@@ -0,0 +1,23 @@
+; This file is part of the CircuitPython project: https://circuitpython.org
+;
+; SPDX-FileCopyrightText: Copyright (c) 2026 Tim Cocks for Adafruit Industries
+;
+; SPDX-License-Identifier: MIT
+
+.program i2sin_left
+.side_set 2
+
+; Master-mode I2S RX, left-justified. Mirrors the timing of i2s_left.pio.
+                    ;        /--- LRCLK
+                    ;        |/-- BCLK
+                    ;        ||
+    set y 14          side 0b00
+bitloop1:
+    in pins 1         side 0b11 [2] ; Right channel first
+    jmp y-- bitloop1  side 0b10 [2]
+    in pins 1         side 0b11 [2]
+    set y 14          side 0b10 [2]
+bitloop0:
+    in pins 1         side 0b01 [2] ; Then left channel
+    jmp y-- bitloop0  side 0b00 [2]
+    in pins 1         side 0b01 [2]
diff --git a/ports/raspberrypi/common-hal/audioi2sin/i2sin_left_32.pio b/ports/raspberrypi/common-hal/audioi2sin/i2sin_left_32.pio
new file mode 100644
index 0000000000000..d2502a21540d8
--- /dev/null
+++ b/ports/raspberrypi/common-hal/audioi2sin/i2sin_left_32.pio
@@ -0,0 +1,23 @@
+; This file is part of the CircuitPython project: https://circuitpython.org
+;
+; SPDX-FileCopyrightText: Copyright (c) 2026 Tim Cocks for Adafruit Industries
+;
+; SPDX-License-Identifier: MIT
+
+.program i2sin_left_32
+.side_set 2
+
+; Master-mode I2S RX, 32 bits per channel, left-justified.
+                    ;        /--- LRCLK
+                    ;        |/-- BCLK
+                    ;        ||
+    set y 30          side 0b00
+bitloop1:
+    in pins 1         side 0b11 [2] ; Right channel first
+    jmp y-- bitloop1  side 0b10 [2]
+    in pins 1         side 0b11 [2]
+    set y 30          side 0b10 [2]
+bitloop0:
+    in pins 1         side 0b01 [2] ; Then left channel
+    jmp y-- bitloop0  side 0b00 [2]
+    in pins 1         side 0b01 [2]
diff --git a/ports/raspberrypi/common-hal/audioi2sin/i2sin_swap.pio b/ports/raspberrypi/common-hal/audioi2sin/i2sin_swap.pio
new file mode 100644
index 0000000000000..cbf3905bdbcc3
--- /dev/null
+++ b/ports/raspberrypi/common-hal/audioi2sin/i2sin_swap.pio
@@ -0,0 +1,24 @@
+; This file is part of the CircuitPython project: https://circuitpython.org
+;
+; SPDX-FileCopyrightText: Copyright (c) 2026 Tim Cocks for Adafruit Industries
+;
+; SPDX-License-Identifier: MIT
+
+.program i2sin_swap
+.side_set 2
+
+; Master-mode I2S RX with the LRCLK and BCLK pin order swapped (BCLK is the
+; higher-numbered GPIO).
+                    ;        /--- BCLK
+                    ;        |/-- LRCLK
+                    ;        ||
+    set y 14          side 0b01
+bitloop1:
+    in pins 1         side 0b11 [2] ; Right channel first
+    jmp y-- bitloop1  side 0b01 [2]
+    in pins 1         side 0b10 [2]
+    set y 14          side 0b00 [2]
+bitloop0:
+    in pins 1         side 0b10 [2] ; Then left channel
+    jmp y-- bitloop0  side 0b00 [2]
+    in pins 1         side 0b11 [2]
diff --git a/ports/raspberrypi/common-hal/audioi2sin/i2sin_swap_32.pio b/ports/raspberrypi/common-hal/audioi2sin/i2sin_swap_32.pio
new file mode 100644
index 0000000000000..4e00a5a8e545d
--- /dev/null
+++ b/ports/raspberrypi/common-hal/audioi2sin/i2sin_swap_32.pio
@@ -0,0 +1,24 @@
+; This file is part of the CircuitPython project: https://circuitpython.org
+;
+; SPDX-FileCopyrightText: Copyright (c) 2026 Tim Cocks for Adafruit Industries
+;
+; SPDX-License-Identifier: MIT
+
+.program i2sin_swap_32
+.side_set 2
+
+; Master-mode I2S RX, 32 bits per channel, with the LRCLK and BCLK pin order
+; swapped (BCLK is the higher-numbered GPIO).
+                    ;        /--- BCLK
+                    ;        |/-- LRCLK
+                    ;        ||
+    set y 30          side 0b01
+bitloop1:
+    in pins 1         side 0b11 [2] ; Right channel first
+    jmp y-- bitloop1  side 0b01 [2]
+    in pins 1         side 0b10 [2]
+    set y 30          side 0b00 [2]
+bitloop0:
+    in pins 1         side 0b10 [2] ; Then left channel
+    jmp y-- bitloop0  side 0b00 [2]
+    in pins 1         side 0b11 [2]
diff --git a/ports/raspberrypi/common-hal/audioi2sin/i2sin_swap_left.pio b/ports/raspberrypi/common-hal/audioi2sin/i2sin_swap_left.pio
new file mode 100644
index 0000000000000..90ae7ea8d0e8e
--- /dev/null
+++ b/ports/raspberrypi/common-hal/audioi2sin/i2sin_swap_left.pio
@@ -0,0 +1,24 @@
+; This file is part of the CircuitPython project: https://circuitpython.org
+;
+; SPDX-FileCopyrightText: Copyright (c) 2026 Tim Cocks for Adafruit Industries
+;
+; SPDX-License-Identifier: MIT
+
+.program i2sin_swap_left
+.side_set 2
+
+; Master-mode I2S RX, left-justified, with the LRCLK and BCLK pin order
+; swapped (BCLK is the higher-numbered GPIO).
+                    ;        /--- BCLK
+                    ;        |/-- LRCLK
+                    ;        ||
+    set y 14          side 0b00
+bitloop1:
+    in pins 1         side 0b11 [2] ; Right channel first
+    jmp y-- bitloop1  side 0b01 [2]
+    in pins 1         side 0b11 [2]
+    set y 14          side 0b01 [2]
+bitloop0:
+    in pins 1         side 0b10 [2] ; Then left channel
+    jmp y-- bitloop0  side 0b00 [2]
+    in pins 1         side 0b10 [2]
diff --git a/ports/raspberrypi/common-hal/audioi2sin/i2sin_swap_left_32.pio b/ports/raspberrypi/common-hal/audioi2sin/i2sin_swap_left_32.pio
new file mode 100644
index 0000000000000..49e0ec7dccf43
--- /dev/null
+++ b/ports/raspberrypi/common-hal/audioi2sin/i2sin_swap_left_32.pio
@@ -0,0 +1,24 @@
+; This file is part of the CircuitPython project: https://circuitpython.org
+;
+; SPDX-FileCopyrightText: Copyright (c) 2026 Tim Cocks for Adafruit Industries
+;
+; SPDX-License-Identifier: MIT
+
+.program i2sin_swap_left_32
+.side_set 2
+
+; Master-mode I2S RX, 32 bits per channel, left-justified, with the LRCLK and
+; BCLK pin order swapped (BCLK is the higher-numbered GPIO).
+                    ;        /--- BCLK
+                    ;        |/-- LRCLK
+                    ;        ||
+    set y 30          side 0b00
+bitloop1:
+    in pins 1         side 0b11 [2] ; Right channel first
+    jmp y-- bitloop1  side 0b01 [2]
+    in pins 1         side 0b11 [2]
+    set y 30          side 0b01 [2]
+bitloop0:
+    in pins 1         side 0b10 [2] ; Then left channel
+    jmp y-- bitloop0  side 0b00 [2]
+    in pins 1         side 0b10 [2]
diff --git a/ports/raspberrypi/common-hal/rp2pio/StateMachine.c b/ports/raspberrypi/common-hal/rp2pio/StateMachine.c
index 71050677f225f..af6e98bbc85cc 100644
--- a/ports/raspberrypi/common-hal/rp2pio/StateMachine.c
+++ b/ports/raspberrypi/common-hal/rp2pio/StateMachine.c
@@ -1482,6 +1482,36 @@ bool common_hal_rp2pio_statemachine_stop_background_read(rp2pio_statemachine_obj
     return true;
 }
 
+void common_hal_rp2pio_statemachine_set_read_buffers_raw(rp2pio_statemachine_obj_t *self,
+    void *once, size_t once_len,
+    void *loop, size_t loop_len,
+    void *loop2, size_t loop2_len) {
+    memset(&self->once_read_buf_info, 0, sizeof(self->once_read_buf_info));
+    memset(&self->loop_read_buf_info, 0, sizeof(self->loop_read_buf_info));
+    memset(&self->loop2_read_buf_info, 0, sizeof(self->loop2_read_buf_info));
+    if (once && once_len) {
+        self->once_read_buf_info.info.buf = once;
+        self->once_read_buf_info.info.len = once_len;
+    }
+    if (loop && loop_len) {
+        self->loop_read_buf_info.info.buf = loop;
+        self->loop_read_buf_info.info.len = loop_len;
+    }
+    if (loop2 && loop2_len) {
+        self->loop2_read_buf_info.info.buf = loop2;
+        self->loop2_read_buf_info.info.len = loop2_len;
+    }
+}
+
+int common_hal_rp2pio_statemachine_get_read_dma_channel(rp2pio_statemachine_obj_t *self) {
+    uint8_t pio_index = pio_get_index(self->pio);
+    uint8_t sm = self->state_machine;
+    if (!SM_DMA_ALLOCATED_READ(pio_index, sm)) {
+        return -1;
+    }
+    return SM_DMA_GET_CHANNEL_READ(pio_index, sm);
+}
+
 bool common_hal_rp2pio_statemachine_get_reading(rp2pio_statemachine_obj_t *self) {
     return !self->dma_completed_read;
 }
diff --git a/ports/raspberrypi/mpconfigport.mk b/ports/raspberrypi/mpconfigport.mk
index 90be1afd10922..76f468beee65b 100644
--- a/ports/raspberrypi/mpconfigport.mk
+++ b/ports/raspberrypi/mpconfigport.mk
@@ -44,6 +44,7 @@ CIRCUITPY_ANALOGBUFIO = 1
 # Audio via PWM
 CIRCUITPY_AUDIOIO = 0
 CIRCUITPY_AUDIOBUSIO ?= 1
+CIRCUITPY_AUDIOI2SIN ?= $(CIRCUITPY_AUDIOBUSIO)
 CIRCUITPY_AUDIOCORE ?= 1
 CIRCUITPY_AUDIOPWMIO ?= 1
 
diff --git a/py/circuitpy_defns.mk b/py/circuitpy_defns.mk
index e0ad8fa81bc10..67be45325d565 100644
--- a/py/circuitpy_defns.mk
+++ b/py/circuitpy_defns.mk
@@ -122,6 +122,9 @@ endif
 ifeq ($(CIRCUITPY_AUDIOBUSIO),1)
 SRC_PATTERNS += audiobusio/%
 endif
+ifeq ($(CIRCUITPY_AUDIOI2SIN),1)
+SRC_PATTERNS += audioi2sin/%
+endif
 ifeq ($(CIRCUITPY_AUDIOIO),1)
 SRC_PATTERNS += audioio/%
 endif
@@ -505,6 +508,8 @@ SRC_COMMON_HAL_ALL = \
 	audiobusio/I2SOut.c \
 	audiobusio/PDMIn.c \
 	audiobusio/__init__.c \
+	audioi2sin/I2SIn.c \
+	audioi2sin/__init__.c \
 	audioio/AudioOut.c \
 	audioio/__init__.c \
 	audiopwmio/PWMAudioOut.c \
diff --git a/py/circuitpy_mpconfig.mk b/py/circuitpy_mpconfig.mk
index 170122903286b..f56813f3b9174 100644
--- a/py/circuitpy_mpconfig.mk
+++ b/py/circuitpy_mpconfig.mk
@@ -135,6 +135,10 @@ CFLAGS += -DCIRCUITPY_AUDIOBUSIO_I2SOUT=$(CIRCUITPY_AUDIOBUSIO_I2SOUT)
 CIRCUITPY_AUDIOBUSIO_PDMIN ?= $(CIRCUITPY_AUDIOBUSIO)
 CFLAGS += -DCIRCUITPY_AUDIOBUSIO_PDMIN=$(CIRCUITPY_AUDIOBUSIO_PDMIN)
 
+# I2S audio input (separate core module `audioi2sin`).
+CIRCUITPY_AUDIOI2SIN ?= 0
+CFLAGS += -DCIRCUITPY_AUDIOI2SIN=$(CIRCUITPY_AUDIOI2SIN)
+
 CIRCUITPY_AUDIOIO ?= $(CIRCUITPY_FULL_BUILD)
 CFLAGS += -DCIRCUITPY_AUDIOIO=$(CIRCUITPY_AUDIOIO)
 
diff --git a/shared-bindings/audioi2sin/I2SIn.c b/shared-bindings/audioi2sin/I2SIn.c
new file mode 100644
index 0000000000000..16ba7bf76f341
--- /dev/null
+++ b/shared-bindings/audioi2sin/I2SIn.c
@@ -0,0 +1,315 @@
+// This file is part of the CircuitPython project: https://circuitpython.org
+//
+// SPDX-FileCopyrightText: Copyright (c) 2026 Tim Cocks for Adafruit Industries
+//
+// SPDX-License-Identifier: MIT
+
+#include <stdint.h>
+
+#include "extmod/vfs_fat.h"
+#include "shared/runtime/context_manager_helpers.h"
+#include "py/binary.h"
+#include "py/mphal.h"
+#include "py/objproperty.h"
+#include "py/runtime.h"
+#include "shared-bindings/microcontroller/Pin.h"
+#include "shared-bindings/audioi2sin/I2SIn.h"
+#include "shared-bindings/util.h"
+
+//| class I2SIn:
+//|     """Record an input I2S audio stream from an external I2S source such as a MEMS microphone."""
+//|
+//|     def __init__(
+//|         self,
+//|         bit_clock: microcontroller.Pin,
+//|         word_select: microcontroller.Pin,
+//|         data: microcontroller.Pin,
+//|         *,
+//|         main_clock: Optional[microcontroller.Pin] = None,
+//|         sample_rate: int = 16000,
+//|         bit_depth: int = 16,
+//|         output_bit_depth: Optional[int] = None,
+//|         mono: bool = True,
+//|         left_justified: bool = False,
+//|         samples_signed: bool = True,
+//|     ) -> None:
+//|         """Create an I2SIn object associated with the given pins. This allows you to
+//|         record audio signals from an external I2S source (e.g. an I2S MEMS microphone
+//|         like the SPH0645LM4H or INMP441).
+//|
+//|         The pin signature mirrors `audiobusio.I2SOut` so users can swap classes;
+//|         recording parameters mirror `audiobusio.PDMIn`.
+//|
+//|         :param ~microcontroller.Pin bit_clock: The bit clock (or serial clock) pin
+//|         :param ~microcontroller.Pin word_select: The word select (or left/right clock) pin
+//|         :param ~microcontroller.Pin data: The data input pin
+//|         :param ~microcontroller.Pin main_clock: The main clock pin. Not all ports support this.
+//|         :param int sample_rate: Target sample rate of the resulting samples. Check `sample_rate` for actual value.
+//|         :param int bit_depth: Number of bits per sample on the I2S bus. Must be 8, 16, 24, or
+//|           32. 8-bit only supported on espressif. The destination buffer typecode is determined
+//|           by ``output_bit_depth`` (or ``bit_depth`` when ``output_bit_depth`` is ``None``):
+//|
+//|           +----------------+------------------+----------------------+
+//|           | samples_signed | output_bit_depth | Required typecode(s) |
+//|           +================+==================+======================+
+//|           | True           | 24 or 32         | ``'i'``              |
+//|           +----------------+------------------+----------------------+
+//|           | True           | 16               | ``'h'``              |
+//|           +----------------+------------------+----------------------+
+//|           | True           | 8                | ``'b'`` or BYTEARRAY |
+//|           +----------------+------------------+----------------------+
+//|           | False          | 24 or 32         | ``'I'``              |
+//|           +----------------+------------------+----------------------+
+//|           | False          | 16               | ``'H'``              |
+//|           +----------------+------------------+----------------------+
+//|           | False          | 8                | ``'B'`` or BYTEARRAY |
+//|           +----------------+------------------+----------------------+
+//|
+//|           Note that 24-bit samples from mics like the SPH0645LM4H / INMP441 are
+//|           transported in 32-bit slots, so use ``bit_depth=32`` and an ``'I'`` buffer.
+//|         :param int output_bit_depth: If set, recorded samples are bit-shifted from
+//|           ``bit_depth`` to this width before being written to the destination buffer
+//|           (8, 16, 24, or 32). Widening pads the new LSBs with zero; narrowing arithmetic-
+//|           shifts the value right (sign-preserving when ``samples_signed`` is True). When
+//|           ``None`` (the default) the destination buffer holds samples at ``bit_depth``.
+//|         :param bool mono: True when capturing a single channel of audio, captures two channels otherwise.
+//|         :param bool left_justified: True when data bits are aligned with the word select clock. False
+//|           when they are shifted by one to match classic I2S protocol. Set True for mics like the SPH0645LM4H.
+//|         :param bool samples_signed: Samples are signed (True) or unsigned (False). I2S mics deliver signed
+//|           two's-complement PCM natively; set False to have the recorded samples converted to unsigned PCM
+//|           (the top/sign bit is flipped, matching the WAV convention for unsigned samples).
+//|
+//|         Example, recording 16-bit mono samples from an INMP441::
+//|
+//|           import array
+//|           import audioi2sin
+//|           import board
+//|
+//|           buf = array.array("h", [0] * 16000)
+//|           with audioi2sin.I2SIn(board.D9, board.D10, board.D11,
+//|                                  sample_rate=16000, bit_depth=16) as mic:
+//|               mic.record(buf, len(buf))
+//|
+//|         """
+//|         ...
+//|
+static mp_obj_t audioi2sin_i2sin_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *all_args) {
+    #if !CIRCUITPY_AUDIOI2SIN
+    mp_raise_NotImplementedError_varg(MP_ERROR_TEXT("%q"), MP_QSTR_I2SIn);
+    return NULL; // Not reachable.
+    #else
+    enum { ARG_bit_clock, ARG_word_select, ARG_data, ARG_main_clock,
+           ARG_sample_rate, ARG_bit_depth, ARG_output_bit_depth,
+           ARG_mono, ARG_left_justified, ARG_samples_signed };
+    static const mp_arg_t allowed_args[] = {
+        { MP_QSTR_bit_clock,        MP_ARG_REQUIRED | MP_ARG_OBJ },
+        { MP_QSTR_word_select,      MP_ARG_REQUIRED | MP_ARG_OBJ },
+        { MP_QSTR_data,             MP_ARG_REQUIRED | MP_ARG_OBJ },
+        { MP_QSTR_main_clock,       MP_ARG_KW_ONLY | MP_ARG_OBJ,  {.u_obj = mp_const_none} },
+        { MP_QSTR_sample_rate,      MP_ARG_KW_ONLY | MP_ARG_INT,  {.u_int = 16000} },
+        { MP_QSTR_bit_depth,        MP_ARG_KW_ONLY | MP_ARG_INT,  {.u_int = 16} },
+        { MP_QSTR_output_bit_depth, MP_ARG_KW_ONLY | MP_ARG_OBJ,  {.u_obj = mp_const_none} },
+        { MP_QSTR_mono,             MP_ARG_KW_ONLY | MP_ARG_BOOL, {.u_bool = true} },
+        { MP_QSTR_left_justified,   MP_ARG_KW_ONLY | MP_ARG_BOOL, {.u_bool = false} },
+        { MP_QSTR_samples_signed,   MP_ARG_KW_ONLY | MP_ARG_BOOL, {.u_bool = true} },
+    };
+    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
+    mp_arg_parse_all_kw_array(n_args, n_kw, all_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
+
+    const mcu_pin_obj_t *bit_clock = validate_obj_is_free_pin(args[ARG_bit_clock].u_obj, MP_QSTR_bit_clock);
+    const mcu_pin_obj_t *word_select = validate_obj_is_free_pin(args[ARG_word_select].u_obj, MP_QSTR_word_select);
+    const mcu_pin_obj_t *data = validate_obj_is_free_pin(args[ARG_data].u_obj, MP_QSTR_data);
+    const mcu_pin_obj_t *main_clock = validate_obj_is_free_pin_or_none(args[ARG_main_clock].u_obj, MP_QSTR_main_clock);
+
+    uint32_t sample_rate = args[ARG_sample_rate].u_int;
+    uint8_t bit_depth = args[ARG_bit_depth].u_int;
+    if (bit_depth != 8 && bit_depth != 16 && bit_depth != 24 && bit_depth != 32) {
+        mp_raise_ValueError_varg(MP_ERROR_TEXT("%q must be 8, 16, 24, or 32"), MP_QSTR_bit_depth);
+    }
+    uint8_t output_bit_depth;
+    mp_obj_t output_bit_depth_obj = args[ARG_output_bit_depth].u_obj;
+    if (output_bit_depth_obj == mp_const_none) {
+        output_bit_depth = bit_depth;
+    } else {
+        mp_int_t v = mp_obj_get_int(output_bit_depth_obj);
+        if (v != 8 && v != 16 && v != 24 && v != 32) {
+            mp_raise_ValueError_varg(MP_ERROR_TEXT("%q must be 8, 16, 24, or 32"), MP_QSTR_output_bit_depth);
+        }
+        output_bit_depth = (uint8_t)v;
+    }
+    bool mono = args[ARG_mono].u_bool;
+    bool left_justified = args[ARG_left_justified].u_bool;
+    bool samples_signed = args[ARG_samples_signed].u_bool;
+
+    audioi2sin_i2sin_obj_t *self = mp_obj_malloc_with_finaliser(audioi2sin_i2sin_obj_t, &audioi2sin_i2sin_type);
+    common_hal_audioi2sin_i2sin_construct(self, bit_clock, word_select, data, main_clock,
+        sample_rate, bit_depth, output_bit_depth, mono, left_justified, samples_signed);
+
+    return MP_OBJ_FROM_PTR(self);
+    #endif
+}
+
+#if CIRCUITPY_AUDIOI2SIN
+//|     def deinit(self) -> None:
+//|         """Deinitialises the I2SIn and releases any hardware resources for reuse."""
+//|         ...
+//|
+static mp_obj_t audioi2sin_i2sin_deinit(mp_obj_t self_in) {
+    audioi2sin_i2sin_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    common_hal_audioi2sin_i2sin_deinit(self);
+    return mp_const_none;
+}
+static MP_DEFINE_CONST_FUN_OBJ_1(audioi2sin_i2sin_deinit_obj, audioi2sin_i2sin_deinit);
+
+static void check_for_deinit(audioi2sin_i2sin_obj_t *self) {
+    if (common_hal_audioi2sin_i2sin_deinited(self)) {
+        raise_deinited_error();
+    }
+}
+
+//|     def __enter__(self) -> I2SIn:
+//|         """No-op used by Context Managers."""
+//|         ...
+//|
+//  Provided by context manager helper.
+
+//|     def __exit__(self) -> None:
+//|         """Automatically deinitializes the hardware when exiting a context. See
+//|         :ref:`lifetime-and-contextmanagers` for more info."""
+//|         ...
+//|
+//  Provided by context manager helper.
+
+//|     def record(self, destination: WriteableBuffer, destination_length: int) -> int:
+//|         """Records destination_length samples to destination. This is blocking.
+//|
+//|         :return: The number of samples recorded. If this is less than ``destination_length``,
+//|           some samples were missed due to processing time."""
+//|         ...
+//|
+static mp_obj_t audioi2sin_i2sin_obj_record(mp_obj_t self_obj, mp_obj_t destination, mp_obj_t destination_length) {
+    audioi2sin_i2sin_obj_t *self = MP_OBJ_TO_PTR(self_obj);
+    check_for_deinit(self);
+    uint32_t length = mp_arg_validate_type_int(destination_length, MP_QSTR_length);
+    mp_arg_validate_length_min(length, 0, MP_QSTR_length);
+
+    mp_buffer_info_t bufinfo;
+    if (mp_obj_is_type(destination, &mp_type_fileio)) {
+        mp_raise_NotImplementedError(MP_ERROR_TEXT("Cannot record to a file"));
+    }
+    mp_get_buffer_raise(destination, &bufinfo, MP_BUFFER_WRITE);
+    if (bufinfo.len / mp_binary_get_size('@', bufinfo.typecode, NULL) < length) {
+        mp_raise_ValueError(MP_ERROR_TEXT("Destination capacity is smaller than destination_length."));
+    }
+    uint8_t output_bit_depth = common_hal_audioi2sin_i2sin_get_output_bit_depth(self);
+    char error_type = ' ';
+    bool samples_signed = common_hal_audioi2sin_i2sin_get_samples_signed(self);
+    if (samples_signed) {
+        if ((output_bit_depth == 24 || output_bit_depth == 32) && bufinfo.typecode != 'i') {
+            error_type = 'i';
+        } else if (output_bit_depth == 16 && bufinfo.typecode != 'h') {
+            error_type = 'h';
+        } else if (output_bit_depth == 8 && bufinfo.typecode != 'b' && bufinfo.typecode != BYTEARRAY_TYPECODE) {
+            error_type = 'b'; // NOTE: Not identifying as bytearray
+        }
+    } else {
+        if ((output_bit_depth == 24 || output_bit_depth == 32) && bufinfo.typecode != 'I') {
+            error_type = 'I';
+        } else if (output_bit_depth == 16 && bufinfo.typecode != 'H') {
+            error_type = 'H';
+        } else if (output_bit_depth == 8 && bufinfo.typecode != 'B' && bufinfo.typecode != BYTEARRAY_TYPECODE) {
+            error_type = 'B';
+        }
+    }
+    if (error_type != ' ') {
+        mp_raise_TypeError_varg(
+            MP_ERROR_TEXT("invalid destination buffer, must be an array of type: %c"),
+            error_type
+            );
+    }
+    uint32_t length_written =
+        common_hal_audioi2sin_i2sin_record_to_buffer(self, bufinfo.buf, length);
+    return MP_OBJ_NEW_SMALL_INT(length_written);
+}
+MP_DEFINE_CONST_FUN_OBJ_3(audioi2sin_i2sin_record_obj, audioi2sin_i2sin_obj_record);
+
+//|     sample_rate: int
+//|     """The actual sample rate of the recording. This may not match the constructed
+//|     sample rate due to internal clock limitations."""
+//|
+static mp_obj_t audioi2sin_i2sin_obj_get_sample_rate(mp_obj_t self_in) {
+    audioi2sin_i2sin_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    check_for_deinit(self);
+    return MP_OBJ_NEW_SMALL_INT(common_hal_audioi2sin_i2sin_get_sample_rate(self));
+}
+MP_DEFINE_CONST_FUN_OBJ_1(audioi2sin_i2sin_get_sample_rate_obj, audioi2sin_i2sin_obj_get_sample_rate);
+
+MP_PROPERTY_GETTER(audioi2sin_i2sin_sample_rate_obj,
+    (mp_obj_t)&audioi2sin_i2sin_get_sample_rate_obj);
+
+//|     bit_depth: int
+//|     """The actual bit depth of the recording. (read-only)"""
+//|
+//|
+static mp_obj_t audioi2sin_i2sin_obj_get_bit_depth(mp_obj_t self_in) {
+    audioi2sin_i2sin_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    check_for_deinit(self);
+    return MP_OBJ_NEW_SMALL_INT(common_hal_audioi2sin_i2sin_get_bit_depth(self));
+}
+MP_DEFINE_CONST_FUN_OBJ_1(audioi2sin_i2sin_get_bit_depth_obj, audioi2sin_i2sin_obj_get_bit_depth);
+
+MP_PROPERTY_GETTER(audioi2sin_i2sin_bit_depth_obj,
+    (mp_obj_t)&audioi2sin_i2sin_get_bit_depth_obj);
+
+//|     output_bit_depth: int
+//|     """The bit depth of samples written to the destination buffer. Equals ``bit_depth`` when
+//|     ``output_bit_depth`` was not supplied (or was ``None``) at construction time. (read-only)"""
+//|
+//|
+static mp_obj_t audioi2sin_i2sin_obj_get_output_bit_depth(mp_obj_t self_in) {
+    audioi2sin_i2sin_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    check_for_deinit(self);
+    return MP_OBJ_NEW_SMALL_INT(common_hal_audioi2sin_i2sin_get_output_bit_depth(self));
+}
+MP_DEFINE_CONST_FUN_OBJ_1(audioi2sin_i2sin_get_output_bit_depth_obj, audioi2sin_i2sin_obj_get_output_bit_depth);
+
+MP_PROPERTY_GETTER(audioi2sin_i2sin_output_bit_depth_obj,
+    (mp_obj_t)&audioi2sin_i2sin_get_output_bit_depth_obj);
+
+//|     samples_signed: bool
+//|     """True if recorded samples are signed PCM, False for unsigned. (read-only)"""
+//|
+//|
+static mp_obj_t audioi2sin_i2sin_obj_get_samples_signed(mp_obj_t self_in) {
+    audioi2sin_i2sin_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    check_for_deinit(self);
+    return mp_obj_new_bool(common_hal_audioi2sin_i2sin_get_samples_signed(self));
+}
+MP_DEFINE_CONST_FUN_OBJ_1(audioi2sin_i2sin_get_samples_signed_obj, audioi2sin_i2sin_obj_get_samples_signed);
+
+MP_PROPERTY_GETTER(audioi2sin_i2sin_samples_signed_obj,
+    (mp_obj_t)&audioi2sin_i2sin_get_samples_signed_obj);
+
+static const mp_rom_map_elem_t audioi2sin_i2sin_locals_dict_table[] = {
+    { MP_ROM_QSTR(MP_QSTR___del__), MP_ROM_PTR(&audioi2sin_i2sin_deinit_obj) },
+    { MP_ROM_QSTR(MP_QSTR_deinit), MP_ROM_PTR(&audioi2sin_i2sin_deinit_obj) },
+    { MP_ROM_QSTR(MP_QSTR___enter__), MP_ROM_PTR(&default___enter___obj) },
+    { MP_ROM_QSTR(MP_QSTR___exit__), MP_ROM_PTR(&default___exit___obj) },
+    { MP_ROM_QSTR(MP_QSTR_record), MP_ROM_PTR(&audioi2sin_i2sin_record_obj) },
+    { MP_ROM_QSTR(MP_QSTR_sample_rate), MP_ROM_PTR(&audioi2sin_i2sin_sample_rate_obj) },
+    { MP_ROM_QSTR(MP_QSTR_bit_depth), MP_ROM_PTR(&audioi2sin_i2sin_bit_depth_obj) },
+    { MP_ROM_QSTR(MP_QSTR_output_bit_depth), MP_ROM_PTR(&audioi2sin_i2sin_output_bit_depth_obj) },
+    { MP_ROM_QSTR(MP_QSTR_samples_signed), MP_ROM_PTR(&audioi2sin_i2sin_samples_signed_obj) },
+};
+static MP_DEFINE_CONST_DICT(audioi2sin_i2sin_locals_dict, audioi2sin_i2sin_locals_dict_table);
+#endif // CIRCUITPY_AUDIOI2SIN
+
+MP_DEFINE_CONST_OBJ_TYPE(
+    audioi2sin_i2sin_type,
+    MP_QSTR_I2SIn,
+    MP_TYPE_FLAG_HAS_SPECIAL_ACCESSORS,
+    make_new, audioi2sin_i2sin_make_new
+    #if CIRCUITPY_AUDIOI2SIN
+    , locals_dict, &audioi2sin_i2sin_locals_dict
+    #endif
+    );
diff --git a/shared-bindings/audioi2sin/I2SIn.h b/shared-bindings/audioi2sin/I2SIn.h
new file mode 100644
index 0000000000000..dc9c671741a36
--- /dev/null
+++ b/shared-bindings/audioi2sin/I2SIn.h
@@ -0,0 +1,31 @@
+// This file is part of the CircuitPython project: https://circuitpython.org
+//
+// SPDX-FileCopyrightText: Copyright (c) 2026 Tim Cocks for Adafruit Industries
+//
+// SPDX-License-Identifier: MIT
+
+#pragma once
+
+#include "shared-bindings/microcontroller/Pin.h"
+
+#if CIRCUITPY_AUDIOI2SIN
+#include "common-hal/audioi2sin/I2SIn.h"
+#endif
+
+extern const mp_obj_type_t audioi2sin_i2sin_type;
+
+#if CIRCUITPY_AUDIOI2SIN
+void common_hal_audioi2sin_i2sin_construct(audioi2sin_i2sin_obj_t *self,
+    const mcu_pin_obj_t *bit_clock, const mcu_pin_obj_t *word_select,
+    const mcu_pin_obj_t *data, const mcu_pin_obj_t *main_clock,
+    uint32_t sample_rate, uint8_t bit_depth, uint8_t output_bit_depth,
+    bool mono, bool left_justified, bool samples_signed);
+void common_hal_audioi2sin_i2sin_deinit(audioi2sin_i2sin_obj_t *self);
+bool common_hal_audioi2sin_i2sin_deinited(audioi2sin_i2sin_obj_t *self);
+uint32_t common_hal_audioi2sin_i2sin_record_to_buffer(audioi2sin_i2sin_obj_t *self,
+    void *buffer, uint32_t length);
+uint8_t common_hal_audioi2sin_i2sin_get_bit_depth(audioi2sin_i2sin_obj_t *self);
+uint8_t common_hal_audioi2sin_i2sin_get_output_bit_depth(audioi2sin_i2sin_obj_t *self);
+uint32_t common_hal_audioi2sin_i2sin_get_sample_rate(audioi2sin_i2sin_obj_t *self);
+bool common_hal_audioi2sin_i2sin_get_samples_signed(audioi2sin_i2sin_obj_t *self);
+#endif
diff --git a/shared-bindings/audioi2sin/__init__.c b/shared-bindings/audioi2sin/__init__.c
new file mode 100644
index 0000000000000..45ba16cb01aea
--- /dev/null
+++ b/shared-bindings/audioi2sin/__init__.c
@@ -0,0 +1,38 @@
+// This file is part of the CircuitPython project: https://circuitpython.org
+//
+// SPDX-FileCopyrightText: Copyright (c) 2026 Tim Cocks for Adafruit Industries
+//
+// SPDX-License-Identifier: MIT
+
+#include <stdint.h>
+
+#include "py/obj.h"
+#include "py/runtime.h"
+
+#include "shared-bindings/microcontroller/Pin.h"
+#include "shared-bindings/audioi2sin/__init__.h"
+#include "shared-bindings/audioi2sin/I2SIn.h"
+
+//| """Support for recording audio from an I2S input source.
+//|
+//| The `audioi2sin` module contains the `I2SIn` class for recording audio
+//| from an external I2S source such as a MEMS microphone (e.g. SPH0645LM4H
+//| or INMP441).
+//|
+//| All classes change hardware state and should be deinitialized when they
+//| are no longer needed. To do so, either call :py:meth:`!deinit` or use a
+//| context manager."""
+
+static const mp_rom_map_elem_t audioi2sin_module_globals_table[] = {
+    { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_audioi2sin) },
+    { MP_ROM_QSTR(MP_QSTR_I2SIn), MP_ROM_PTR(&audioi2sin_i2sin_type) },
+};
+
+static MP_DEFINE_CONST_DICT(audioi2sin_module_globals, audioi2sin_module_globals_table);
+
+const mp_obj_module_t audioi2sin_module = {
+    .base = { &mp_type_module },
+    .globals = (mp_obj_dict_t *)&audioi2sin_module_globals,
+};
+
+MP_REGISTER_MODULE(MP_QSTR_audioi2sin, audioi2sin_module);
diff --git a/shared-bindings/audioi2sin/__init__.h b/shared-bindings/audioi2sin/__init__.h
new file mode 100644
index 0000000000000..779b49ffd8db3
--- /dev/null
+++ b/shared-bindings/audioi2sin/__init__.h
@@ -0,0 +1,7 @@
+// This file is part of the CircuitPython project: https://circuitpython.org
+//
+// SPDX-FileCopyrightText: Copyright (c) 2026 Tim Cocks for Adafruit Industries
+//
+// SPDX-License-Identifier: MIT
+
+#pragma once
diff --git a/tests/circuitpython-manual/audioi2sin/i2sin_neopixel_reactive.py b/tests/circuitpython-manual/audioi2sin/i2sin_neopixel_reactive.py
new file mode 100644
index 0000000000000..fc5559c70b1ed
--- /dev/null
+++ b/tests/circuitpython-manual/audioi2sin/i2sin_neopixel_reactive.py
@@ -0,0 +1,100 @@
+# SPDX-FileCopyrightText: Copyright (c) 2026 Tim Cocks for Adafruit Industries
+#
+# SPDX-License-Identifier: MIT
+
+# Audio-reactive NeoPixel effect driven by an I2S MEMS microphone.
+#
+# Wiring (defaults assume an INMP441 / SPH0645 style mic):
+#   mic BCLK  -> board.D5
+#   mic LRCL  -> board.D6
+#   mic DOUT  -> board.D9
+#   neopixel  -> board.D10
+#
+# The mic's 24-bit samples ride in 32-bit slots, so we use bit_depth=32 and
+# an array.array("I", ...). For SPH0645 set left_justified=True.
+
+import array
+import math
+import time
+
+import board
+import audioi2sin
+import neopixel
+
+NUM_PIXELS = 30
+PIXEL_PIN = board.D10
+
+SAMPLE_RATE = 16000
+SAMPLES_PER_FRAME = 512  # ~32 ms windows
+
+pixels = neopixel.NeoPixel(PIXEL_PIN, NUM_PIXELS, brightness=0.3, auto_write=False)
+
+mic = audioi2sin.I2SIn(
+    bit_clock=board.D5,
+    word_select=board.D6,
+    data=board.D9,
+    sample_rate=SAMPLE_RATE,
+    bit_depth=32,
+    mono=True,
+    left_justified=False,  # set True for SPH0645LM4H
+)
+
+buf = array.array("i", [0] * SAMPLES_PER_FRAME)
+
+
+def wheel(pos):
+    pos = pos % 256
+    if pos < 85:
+        return (pos * 3, 255 - pos * 3, 0)
+    if pos < 170:
+        pos -= 85
+        return (255 - pos * 3, 0, pos * 3)
+    pos -= 170
+    return (0, pos * 3, 255 - pos * 3)
+
+
+# Smoothed noise floor + peak so the effect adapts to the room.
+noise_floor = 2000.0
+peak = 20000.0
+hue = 0
+smoothed_level = 0.0
+
+while True:
+    mic.record(buf, len(buf))
+
+    # Compute RMS of the window.
+    acc = 0
+    for s in buf:
+        acc += s * s
+    rms = math.sqrt(acc / len(buf))
+
+    # Track a slow noise floor and a decaying peak for auto-gain.
+    noise_floor = 0.995 * noise_floor + 0.005 * rms
+    if rms > peak:
+        peak = rms
+    else:
+        peak *= 0.995
+    if peak < noise_floor + 1000:
+        peak = noise_floor + 1000
+
+    level = (rms - noise_floor) / (peak - noise_floor)
+    if level < 0:
+        level = 0.0
+    elif level > 1:
+        level = 1.0
+
+    # Smooth the bar so it doesn't jitter on every frame.
+    smoothed_level = 0.6 * smoothed_level + 0.4 * level
+
+    lit = int(smoothed_level * NUM_PIXELS)
+    hue = (hue + 2) % 256
+
+    for i in range(NUM_PIXELS):
+        if i < lit:
+            r, g, b = wheel((hue + i * (256 // NUM_PIXELS)) % 256)
+            pixels[i] = (r, g, b)
+        else:
+            pixels[i] = (0, 0, 0)
+    pixels.show()
+
+    time.sleep(0.005)
diff --git a/tests/circuitpython-manual/audioi2sin/i2sin_record_sdcard.py b/tests/circuitpython-manual/audioi2sin/i2sin_record_sdcard.py
new file mode 100644
index 0000000000000..c381e272bf78a
--- /dev/null
+++ b/tests/circuitpython-manual/audioi2sin/i2sin_record_sdcard.py
@@ -0,0 +1,105 @@
+# SPDX-FileCopyrightText: Copyright (c) 2026 Tim Cocks for Adafruit Industries
+#
+# SPDX-License-Identifier: MIT
+
+# Record a longer I2S audio capture to a WAV file on an SD card.
+#
+# Produces /sd/recording.wav. Set left_justified=True for SPH0645LM4H mics.
+
+import array
+import struct
+import time
+
+import ulab.numpy as np
+import board
+import busio
+import sdcardio
+import storage
+import audioi2sin
+
+# ---- Recording config ------------------------------------------------------
+SAMPLE_RATE = 16000
+RECORD_SECONDS = 10
+CHUNK_SAMPLES = 1024  # samples captured per record() call
+OUTPUT_PATH = "/sd/talk.wav"
+
+# ---- Mount SD --------------------------------------------------------------
+spi = board.SPI()
+sdcard = sdcardio.SDCard(spi, cs=board.D10, baudrate=24_000_000)
+vfs = storage.VfsFat(sdcard)
+storage.mount(vfs, "/sd")
+
+# ---- Mic -------------------------------------------------------------------
+# 24-bit MEMS mics ride in 32-bit slots. Downconvert each slot to a
+# signed 16-bit PCM sample before writing.
+mic = audioi2sin.I2SIn(
+    bit_clock=board.D5,
+    word_select=board.D6,
+    data=board.D9,
+    sample_rate=SAMPLE_RATE,
+    bit_depth=32,
+    mono=True,
+    left_justified=False,  # True for SPH0645LM4H
+)
+
+actual_rate = mic.sample_rate
+print("Recording at", actual_rate, "Hz for", RECORD_SECONDS, "s ->", OUTPUT_PATH)
+
+raw = array.array("i", [0] * CHUNK_SAMPLES)
+pcm16 = array.array("h", [0] * CHUNK_SAMPLES)
+
+
+def write_wav_header(f, sample_rate, num_samples, bits_per_sample=16, channels=1):
+    byte_rate = sample_rate * channels * bits_per_sample // 8
+    block_align = channels * bits_per_sample // 8
+    data_size = num_samples * block_align
+    f.write(b"RIFF")
+    f.write(struct.pack("<I", 36 + data_size))
+    f.write(b"WAVE")
+    f.write(b"fmt ")
+    f.write(
+        struct.pack(
+            "<IHHIIHH",
+            16,  # fmt chunk size
+            1,  # PCM
+            channels,
+            sample_rate,
+            byte_rate,
+            block_align,
+            bits_per_sample,
+        )
+    )
+    f.write(b"data")
+    f.write(struct.pack("<I", data_size))
+
+
+total_samples = actual_rate * RECORD_SECONDS
+written = 0
+
+# Open with a write+read header placeholder; we'll seek back at the end to
+# patch in the real sample count.
+with open(OUTPUT_PATH, "wb") as f:
+    write_wav_header(f, actual_rate, 0)  # placeholder; rewritten below
+    start = time.monotonic()
+
+    while written < total_samples:
+        n = mic.record(raw, CHUNK_SAMPLES)
+        # Convert 24-bit-in-32-bit slots to signed int16. Top 16 bits of
+        # each slot are the high bits of the signed 24-bit sample, which
+        # is already a serviceable 16-bit PCM representation.
+        for i in range(n):
+            v = raw[i]
+            s = v >> 16  # take top 16 bits
+            pcm16[i] = s
+        # Write only the valid portion.
+        f.write(memoryview(pcm16)[:n])
+        written += n
+
+    elapsed = time.monotonic() - start
+    # Rewrite header now that we know the true sample count.
+    f.seek(0)
+    write_wav_header(f, actual_rate, written)
+
+storage.umount("/sd")
+
+print("Done. Wrote", written, "samples in", round(elapsed, 2), "s")
diff --git a/tests/circuitpython-manual/audioi2sin/i2sin_record_sdcard_output_bit_depth.py b/tests/circuitpython-manual/audioi2sin/i2sin_record_sdcard_output_bit_depth.py
new file mode 100644
index 0000000000000..cc2d2e78c2966
--- /dev/null
+++ b/tests/circuitpython-manual/audioi2sin/i2sin_record_sdcard_output_bit_depth.py
@@ -0,0 +1,100 @@
+# SPDX-FileCopyrightText: Copyright (c) 2026 Tim Cocks for Adafruit Industries
+#
+# SPDX-License-Identifier: MIT
+
+# Record a longer I2S audio capture to a WAV file on an SD card, using the
+# `output_bit_depth` argument to have the driver downconvert each 32-bit slot
+# to signed 16-bit PCM. Compared to `i2sin_record_sdcard.py`, this avoids the
+# Python-side shift loop and writes directly from the recording buffer.
+#
+# Produces /sd/talk.wav. Set left_justified=True for SPH0645LM4H mics.
+
+import array
+import struct
+import time
+
+import board
+import sdcardio
+import storage
+import audioi2sin
+
+# ---- Recording config ------------------------------------------------------
+SAMPLE_RATE = 16000
+RECORD_SECONDS = 10
+CHUNK_SAMPLES = 1024  # samples captured per record() call
+OUTPUT_PATH = "/sd/talk.wav"
+
+# ---- Mount SD --------------------------------------------------------------
+spi = board.SPI()
+sdcard = sdcardio.SDCard(spi, cs=board.D10, baudrate=24_000_000)
+vfs = storage.VfsFat(sdcard)
+storage.mount(vfs, "/sd")
+
+# ---- Mic -------------------------------------------------------------------
+# 24-bit MEMS mics ride in 32-bit slots. Ask the driver to downconvert each
+# slot to a signed 16-bit PCM sample, so `record()` writes straight into a
+# WAV-ready 'h' buffer.
+mic = audioi2sin.I2SIn(
+    bit_clock=board.D5,
+    word_select=board.D6,
+    data=board.D9,
+    sample_rate=SAMPLE_RATE,
+    bit_depth=32,
+    output_bit_depth=16,
+    mono=True,
+    left_justified=False,  # True for SPH0645LM4H
+)
+
+actual_rate = mic.sample_rate
+print("Recording at", actual_rate, "Hz for", RECORD_SECONDS, "s ->", OUTPUT_PATH)
+
+pcm16 = array.array("h", [0] * CHUNK_SAMPLES)
+
+
+def write_wav_header(f, sample_rate, num_samples, bits_per_sample=16, channels=1):
+    byte_rate = sample_rate * channels * bits_per_sample // 8
+    block_align = channels * bits_per_sample // 8
+    data_size = num_samples * block_align
+    f.write(b"RIFF")
+    f.write(struct.pack("<I", 36 + data_size))
+    f.write(b"WAVE")
+    f.write(b"fmt ")
+    f.write(
+        struct.pack(
+            "<IHHIIHH",
+            16,  # fmt chunk size
+            1,  # PCM
+            channels,
+            sample_rate,
+            byte_rate,
+            block_align,
+            bits_per_sample,
+        )
+    )
+    f.write(b"data")
+    f.write(struct.pack("<I", data_size))
+
+
+total_samples = actual_rate * RECORD_SECONDS
+written = 0
+
+# Open with a write+read header placeholder; we'll seek back at the end to
+# patch in the real sample count.
+with open(OUTPUT_PATH, "wb") as f:
+    write_wav_header(f, actual_rate, 0)  # placeholder; rewritten below
+    start = time.monotonic()
+
+    while written < total_samples:
+        n = mic.record(pcm16, CHUNK_SAMPLES)
+        # Driver already downconverted to int16; write only the valid portion.
+        f.write(memoryview(pcm16)[:n])
+        written += n
+
+    elapsed = time.monotonic() - start
+    # Rewrite header now that we know the true sample count.
+    f.seek(0)
+    write_wav_header(f, actual_rate, written)
+
+storage.umount("/sd")
+
+print("Done. Wrote", written, "samples in", round(elapsed, 2), "s")