Add support for MS5525DSO digital airspeed sensor

src/main/CMakeLists.txt

@@ -217,6 +217,8 @@ main_sources(COMMON_SRC
     drivers/pitotmeter/pitotmeter_adc.h
     drivers/pitotmeter/pitotmeter_ms4525.c
     drivers/pitotmeter/pitotmeter_ms4525.h
+    drivers/pitotmeter/pitotmeter_ms5525.c
+    drivers/pitotmeter/pitotmeter_ms5525.h
     drivers/pitotmeter/pitotmeter_dlvr_l10d.c
     drivers/pitotmeter/pitotmeter_dlvr_l10d.h
     drivers/pitotmeter/pitotmeter_msp.c

src/main/drivers/bus.h

@@ -140,6 +140,7 @@ typedef enum {
 
     /* Other hardware */
     DEVHW_MS4525,       // Pitot meter
+    DEVHW_MS5525,       // Pitot meter
     DEVHW_DLVR,         // Pitot meter
     DEVHW_M25P16,       // SPI NOR flash
     DEVHW_W25N,         // SPI 128MB or 256MB flash from Winbond W25N family

src/main/drivers/pitotmeter/pitotmeter_ms5525.c

@@ -0,0 +1,222 @@
+/*
+ * This file is part of INAV.
+ *
+ * INAV is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * INAV is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with INAV.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdbool.h>
+#include <stdint.h>
+
+#include "platform.h"
+#include "build/debug.h"
+
+#include "common/utils.h"
+#include "common/maths.h"
+#include "drivers/time.h"
+#include "drivers/bus_i2c.h"
+#include "drivers/pitotmeter/pitotmeter.h"
+#include "drivers/pitotmeter/pitotmeter_ms5525.h"
+
+// MS5525 I2C Addresses
+#define MS5525_ADDR_1             0x76
+#define MS5525_ADDR_2             0x77
+
+#define CMD_RESET               0x1E // ADC reset command
+#define CMD_ADC_READ            0x00 // ADC read command
+#define CMD_ADC_CONV            0x40 // ADC conversion command
+#define CMD_ADC_D1              0x00 // ADC D1 conversion (Pressure)
+#define CMD_ADC_D2              0x10 // ADC D2 conversion (Temperature)
+#define CMD_ADC_4096            0x08 // ADC OSR=4096
+#define CMD_PROM_RD             0xA0 // Prom read command
+#define PROM_NB                 8
+
+typedef struct __attribute__ ((__packed__)) ms5525Ctx_s {
+    uint16_t c[6]; // c1 through c6
+    uint32_t up;   // up (24 bits) + step (top 8 bits)
+    uint32_t ut;   // ut (24 bits)
+} ms5525Ctx_t;
+
+STATIC_ASSERT(sizeof(ms5525Ctx_t) <= BUS_SCRATCHPAD_MEMORY_SIZE, busDevice_scratchpad_memory_too_small);
+
+static int8_t ms5525_crc(uint16_t *prom)
+{
+    int32_t i, j;
+    uint32_t res = 0;
+    uint8_t crc = prom[7] & 0xF;
+    prom[7] &= 0xFF00;
+
+    bool blankEeprom = true;
+
+    for (i = 0; i < 16; i++) {
+        if (prom[i >> 1]) {
+            blankEeprom = false;
+        }
+        if (i & 1)
+            res ^= ((prom[i >> 1]) & 0x00FF);
+        else
+            res ^= (prom[i >> 1] >> 8);
+        for (j = 8; j > 0; j--) {
+            if (res & 0x8000)
+                res ^= 0x1800;
+            res <<= 1;
+        }
+    }
+    prom[7] |= crc;
+    if (!blankEeprom && crc == ((res >> 12) & 0xF))
+        return 0;
+
+    return -1;
+}
+
+static bool ms5525_read_adc(pitotDev_t *pitot, uint32_t *result)
+{
+    uint8_t rxbuf[3];
+    if (busReadBuf(pitot->busDev, CMD_ADC_READ, rxbuf, 3)) {
+        *result = (rxbuf[0] << 16) | (rxbuf[1] << 8) | rxbuf[2];
+        return true;
+    }
+    return false;
+}
+
+static bool ms5525_start(pitotDev_t * pitot)
+{
+    ms5525Ctx_t * ctx = busDeviceGetScratchpadMemory(pitot->busDev);
+    uint8_t step = ctx->up >> 24;
+
+    if (step == 0) {
+        return busWrite(pitot->busDev, CMD_ADC_CONV + CMD_ADC_D1 + CMD_ADC_4096, 1);
+    } else {
+        return busWrite(pitot->busDev, CMD_ADC_CONV + CMD_ADC_D2 + CMD_ADC_4096, 1);
+    }
+}
+
+static bool ms5525_read(pitotDev_t * pitot)
+{
+    ms5525Ctx_t * ctx = busDeviceGetScratchpadMemory(pitot->busDev);
+    uint8_t step = ctx->up >> 24;
+
+    uint32_t adc_val = 0;
+    if (!ms5525_read_adc(pitot, &adc_val)) {
+        return false;
+    }
+
+    if (step == 0) {
+        ctx->up = adc_val | (1 << 24);
+        return true; 
+    } else {
+        ctx->ut = adc_val;
+        ctx->up &= 0x00FFFFFF; // clear step back to 0
+        return true; 
+    }
+}
+
+static void ms5525_calculate(pitotDev_t * pitot, float *pressure, float *temperature)
+{
+    ms5525Ctx_t * ctx = busDeviceGetScratchpadMemory(pitot->busDev);
+
+    uint32_t up = ctx->up & 0x00FFFFFF;
+    uint32_t ut = ctx->ut;
+
+    if (up == 0 || ut == 0) {
+        return; // Wait until both are read at least once
+    }
+
+    // 5525DSO-pp001DS coefficients (1 psi):
+    // Q1=15, Q2=17, Q3=7, Q4=5, Q5=7, Q6=21
+    int64_t dT   = (int64_t)ut - ((int64_t)ctx->c[4] << 7); // c[5] is c[4] (0-indexed)
+    int64_t off  = ((int64_t)ctx->c[1] << 17) + (((int64_t)ctx->c[3] * dT) >> 5); // c[2]=c[1], c[4]=c[3]
+    int64_t sens = ((int64_t)ctx->c[0] << 15) + (((int64_t)ctx->c[2] * dT) >> 7); // c[1]=c[0], c[3]=c[2]
+    int64_t temp = 2000 + ((dT * (int64_t)ctx->c[5]) >> 21); // c[6]=c[5]
+
+    int64_t p_raw = ((((int64_t)up * sens) >> 21) - off) >> 15;
+
+    // Convert 1 PSI sensor output to Pa
+    // 1 psi = 6894.757 Pa. p_raw is 0.0001 psi per bit -> 0.6894757 Pa per bit.
+
+    if (pressure) {
+        *pressure = (float)p_raw * 0.6894757f;
+    }
+
+    if (temperature) {
+        *temperature = C_TO_KELVIN(temp / 100.0f);
+    }
+}
+
+static bool deviceDetect(busDevice_t * dev)
+{
+    // Verify an I2C transaction works: read PROM
+    uint8_t rxbuf[2];
+    bool ack = busReadBuf(dev, CMD_PROM_RD, rxbuf, 2);
+    if (ack) {
+        return true;
+    }
+    return false;
+}
+
+bool ms5525Detect(pitotDev_t * pitot)
+{
+    pitot->busDev = busDeviceInit(BUSTYPE_I2C, DEVHW_MS5525, 0, OWNER_AIRSPEED);
+    if (pitot->busDev == NULL) {
+        return false;
+    }
+
+    // Try primary address 0x76
+    pitot->busDev->busdev.i2c.address = MS5525_ADDR_1;
+    if (!deviceDetect(pitot->busDev)) {
+        // Fallback to secondary 0x77
+        pitot->busDev->busdev.i2c.address = MS5525_ADDR_2;
+        if (!deviceDetect(pitot->busDev)) {
+            busDeviceDeInit(pitot->busDev);
+            return false;
+        }
+    }
+
+    // Sensor found, initialize
+    busWrite(pitot->busDev, CMD_RESET, 1);
+    delay(5);
+
+    ms5525Ctx_t * ctx = busDeviceGetScratchpadMemory(pitot->busDev);
+
+    // Read PROM 
+    uint16_t prom[8];
+    for (int i = 0; i < PROM_NB; i++) {
+        uint8_t rxbuf[2] = { 0, 0 };
+        busReadBuf(pitot->busDev, CMD_PROM_RD + i * 2, rxbuf, 2);
+        prom[i] = (rxbuf[0] << 8 | rxbuf[1]);
+    }
+
+    // Check CRC
+    if (ms5525_crc(prom) != 0) {
+        busDeviceDeInit(pitot->busDev);
+        return false;
+    }
+
+    // Copy to ctx starting from c1 to c6
+    for (int i = 0; i < 6; i++) {
+        ctx->c[i] = prom[i+1];
+    }
+
+    // Setup Context
+    ctx->up = 0;
+    ctx->ut = 0;
+
+    // Pitot delays
+    pitot->delay = 10000; // max 9.04ms for OSR4096
+    pitot->calibThreshold = 0.00005f;
+    pitot->start = ms5525_start;
+    pitot->get = ms5525_read;
+    pitot->calculate = ms5525_calculate;
+
+    return true;
+}

src/main/drivers/pitotmeter/pitotmeter_ms5525.h

@@ -0,0 +1,22 @@
+/*
+ * This file is part of INAV.
+ *
+ * INAV is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * INAV is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with INAV.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include "drivers/pitotmeter/pitotmeter.h"
+
+bool ms5525Detect(pitotDev_t *pitot);

src/main/fc/settings.yaml

@@ -17,7 +17,7 @@ tables:
     values: ["NONE", "AUTO", "BMP085", "MS5611", "BMP280", "MS5607", "LPS25H", "SPL06", "BMP388", "DPS310", "B2SMPB", "MSP", "FAKE"]
     enum: baroSensor_e
   - name: pitot_hardware
-    values: ["NONE", "AUTO", "MS4525", "ADC", "VIRTUAL", "FAKE", "MSP", "DLVR-L10D"]
+    values: ["NONE", "AUTO", "MS4525", "ADC", "VIRTUAL", "FAKE", "MSP", "DLVR-L10D", "MS5525"]
     enum: pitotSensor_e
   - name: receiver_type
     values: ["NONE", "SERIAL", "MSP", "SIM (SITL)"]

src/main/sensors/pitotmeter.c

@@ -31,6 +31,7 @@
 
 #include "drivers/pitotmeter/pitotmeter.h"
 #include "drivers/pitotmeter/pitotmeter_ms4525.h"
+#include "drivers/pitotmeter/pitotmeter_ms5525.h"
 #include "drivers/pitotmeter/pitotmeter_dlvr_l10d.h"
 #include "drivers/pitotmeter/pitotmeter_adc.h"
 #include "drivers/pitotmeter/pitotmeter_msp.h"
@@ -111,6 +112,19 @@ bool pitotDetect(pitotDev_t *dev, uint8_t pitotHardwareToUse)
             }
             FALLTHROUGH;
 
+        case PITOT_MS5525:
+#ifdef USE_PITOT_MS5525
+            if (ms5525Detect(dev)) {
+                pitotHardware = PITOT_MS5525;
+                break;
+            }
+#endif
+            /* If we are asked for a specific sensor - break out, otherwise - fall through and continue */
+            if (pitotHardwareToUse != PITOT_AUTODETECT) {
+                break;
+            }
+            FALLTHROUGH;
+
         case PITOT_DLVR:
 
 			// Skip autodetection for DLVR (it is indistinguishable from MS4525) and allow only manual config

src/main/sensors/pitotmeter.h

@@ -32,6 +32,7 @@ typedef enum {
     PITOT_FAKE = 5,
     PITOT_MSP = 6,
     PITOT_DLVR = 7,
+    PITOT_MS5525 = 8,
 } pitotSensor_e;
 
 #define PITOT_MAX  PITOT_FAKE

src/main/target/common.h

@@ -95,6 +95,7 @@
 // Allow default airspeed sensors
 #define USE_PITOT
 #define USE_PITOT_MS4525
+#define USE_PITOT_MS5525
 #define USE_PITOT_MSP
 #define USE_PITOT_DLVR
 

src/main/target/common_hardware.c

@@ -397,6 +397,14 @@
     BUSDEV_REGISTER_I2C(busdev_ms4525,      DEVHW_MS4525,       MS4525_I2C_BUS,     0x28,               NONE,           DEVFLAGS_USE_RAW_REGISTERS,  0);    // Requires 0xFF to passthrough
 #endif
 
+#if defined(PITOT_I2C_BUS) && !defined(MS5525_I2C_BUS)
+    #define MS5525_I2C_BUS PITOT_I2C_BUS
+#endif
+
+#if defined(USE_PITOT_MS5525) && defined(MS5525_I2C_BUS)
+    BUSDEV_REGISTER_I2C(busdev_ms5525,      DEVHW_MS5525,       MS5525_I2C_BUS,     0x76,               NONE,           DEVFLAGS_NONE,               0);
+#endif
+
 
 #if defined(PITOT_I2C_BUS) && !defined(DLVR_I2C_BUS)
     #define DLVR_I2C_BUS PITOT_I2C_BUS