Using Bluefruit52Lib with a Seeed XIAO nRF52840 - HID_KEY_PAGE_DOWN/UP type N & K instead

[SeanMH22]

Operating System

Others

IDE version

Arduino IDE: 2.3.6

Board

Seeed XIAO nRF52840

BSP version

Latest github

Sketch

// PageTurner_BLE_Keyboard_Adafruit.ino
// BLE HID page turner for Adafruit bootloader-based XIAO nRF52840

#include <bluefruit.h> // Include the Adafruit Bluefruit BLE library

// Pin definitions for the pedal switches and onboard LED
#define PEDAL_DOWN_PIN 2 // D02: Pedal/button for Page Down
#define PEDAL_UP_PIN 3 // D03: Pedal/button for Page Up
#define LED_PIN 13 // Onboard LED

BLEHidAdafruit blehid; // Create a BLE HID keyboard object

// Callback for keyboard LED state (e.g., Caps Lock)
// Not used in this project, but required by the library
void set_keyboard_led(uint16_t conn_hdl, uint8_t led_state) {
// Optional: handle keyboard LED state changes here
}

void setup() {
Serial.begin(115200); // Start serial communication for debugging

// Set up pedal pins as inputs with internal pull-up resistors
pinMode(PEDAL_DOWN_PIN, INPUT_PULLUP);
pinMode(PEDAL_UP_PIN, INPUT_PULLUP);
pinMode(LED_PIN, OUTPUT); // Set onboard LED as output

// Initialize BLE hardware
Bluefruit.begin();
Bluefruit.setTxPower(4); // Set BLE transmit power
Bluefruit.setName("PagePedalTurner"); // Set BLE device name

blehid.begin(); // Initialize BLE HID keyboard service
blehid.setKeyboardLedCallback(set_keyboard_led); // Register LED callback

// Set up BLE advertising so devices can discover and connect
Bluefruit.Advertising.addFlags(BLE_GAP_ADV_FLAGS_LE_ONLY_GENERAL_DISC_MODE);
Bluefruit.Advertising.addTxPower();
Bluefruit.Advertising.addAppearance(BLE_APPEARANCE_HID_KEYBOARD);
Bluefruit.Advertising.addService(blehid);

Bluefruit.Advertising.start(0); // Start advertising (0 = never stop)

Serial.println("BLE PageTurner is ready!"); // Print status to serial monitor
}

void loop() {
static bool lastDown = HIGH; // Store previous state of Page Down pedal
static bool lastUp = HIGH; // Store previous state of Page Up pedal

// Read current state of pedals (LOW = pressed, HIGH = released)
bool pedalDown = digitalRead(PEDAL_DOWN_PIN);
bool pedalUp = digitalRead(PEDAL_UP_PIN);

// Turn LED ON if either pedal is pressed, OFF otherwise (for active-low LED)
if (pedalDown == LOW || pedalUp == LOW) {
digitalWrite(LED_PIN, LOW); // ON for active-low LED
} else {
digitalWrite(LED_PIN, HIGH); // OFF for active-low LED
}

// If Page Down pedal was just pressed (falling edge)
if (lastDown == HIGH && pedalDown == LOW) {
blehid.keyPress(HID_KEY_PAGE_DOWN); // Send Page Down key press
delay(10); // Short delay for key press
blehid.keyRelease(); // Release all keys
}
lastDown = pedalDown; // Update last state

// If Page Up pedal was just pressed (falling edge)
if (lastUp == HIGH && pedalUp == LOW) {
blehid.keyPress(HID_KEY_PAGE_UP); // Send Page Up key press
delay(10); // Short delay for key press
blehid.keyRelease(); // Release all keys
}
lastUp = pedalUp; // Update last state

delay(5); // Small delay for debounce and to reduce CPU usage
}

What happened ?

I am trying to prototype a BLE music page turner for tablets using - Seeed_XIAO_nRF52840_bootloader-0.6.2_s140_7.3.0
Seeed XIAO nRF52840

HID_KEY_PAGE_DOWN is giving N and HID_KEY_PAGE_UP displays K

Hope this helps

How to reproduce ?

1. Load the sketch
2. Press Page Down button - sends "N" to both Mac and iPhone
3. Press Page Up button - sends "K" to both Mac and iPhone

Debug Log

No response

Screenshots