8000 Bluetooth Master HID and musical keyboard example (#2195) · TGralla/arduino-pico@f6d13d2 · GitHub
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Bluetooth Master HID and musical keyboard example (earlephilhower#2195)
Adds BluetoothHIDMaster and HIDKeyStream which let the PicoW connect to and use Bluetooth Classic HID devices like keyboards and mice. An example that lets the PicoW use a BT keyboard as a piano is included and shows the use of the new classes.
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‎libraries/BluetoothHIDMaster/examples/KeyboardPiano/KeyboardPiano.ino

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// KeyboardPiano example - Released to the public domain in 2024 by Earle F. Philhower, III
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//
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// Demonstrates using the BluetoothHIDMaster class to use a Bluetooth keyboard as a
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// piano keyboard on the PicoW
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//
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// Hook up a phono plug to GP0 and GP1 (and GND of course...the 1st 3 pins on the PCB)
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// Connect wired earbuds up and connect over BT from your keyboard and play some music.
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#include <BluetoothHIDMaster.h>
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#include <PWMAudio.h>
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// We need the inverse map, borrow from the Keyboard library
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#include <HID_Keyboard.h>
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extern const uint8_t KeyboardLayout_en_US[128];
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BluetoothHIDMaster hid;
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PWMAudio pwm;
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HIDKeyStream keystream;
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int16_t sine[1000]; // One complete precalculated sine wave for oscillator use
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void precalculateSine() {
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for (int i = 0; i < 1000; i++) {
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sine[i] = (int16_t)(2000.0 * sin(i * 2 * 3.14159 / 1000.0)); // Only make amplitude ~1/16 max so we can sum up w/o clipping
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}
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}
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// Simple variable frequency resampling oscillator state
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typedef struct {
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uint32_t key; // Identifier of which key started this tone
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uint32_t pos; // Current sine offset
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uint32_t step; // Delta in fixed point 16p16 format
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} Oscillator;
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Oscillator osc[6]; // Look, ma! 6-note polyphony!
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// Quiet down, now!
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void silenceOscillators() {
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noInterrupts();
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for (int i = 0; i < 6; i++) {
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osc[i].pos = 0;
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osc[i].step = 0;
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}
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interrupts();
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}
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// PWM callback, generates sum of online oscillators
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void fill() {
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int num_samples = pwm.availableForWrite() / 2;
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int16_t buff[32 * 2];
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while (num_samples > 63) {
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// Run in 32 LR sample chunks for speed, less loop overhead
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for (int o = 0; o < 32; o++) {
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int32_t sum = 0;
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for (int i = 0; i < 6; i++) {
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if (osc[i].step) {
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sum += sine[osc[i].pos >> 16];
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osc[i].pos += osc[i].step;
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while (osc[i].pos >= 1000 << 16) {
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osc[i].pos -= 1000 << 16;
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}
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}
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}
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if (sum > 32767) {
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sum = 32767;
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} else if (sum < -32767) {
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sum = -32767;
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}
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buff[o * 2] = (int16_t) sum;
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buff[o * 2 + 1] = (int16_t) sum;
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}
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pwm.write((const uint8_t *)buff, sizeof(buff));
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num_samples -= 64;
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}
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}
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// Mouse callbacks. Could keep track of global mouse position, update a cursor, etc.
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void mm(void *cbdata, int dx, int dy, int dw) {
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(void) cbdata;
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Serial.printf("Mouse: X:%d Y:%d Wheel:%d\n", dx, dy, dw);
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}
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// Buttons are sent separately from movement
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void mb(void *cbdata, int butt, bool down) {
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(void) cbdata;
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Serial.printf("Mouse: Button %d %s\n", butt, down ? "DOWN" : "UP");
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}
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// Convert a hertz floating point into a step fixed point 16p16
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inline uint32_t stepForHz(float hz) {
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const float stepHz = 1000.0 / 44100.0;
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const float step = hz * stepHz;
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return (uint32_t)(step * 65536.0);
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}
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uint32_t keyStepMap[128]; // The frequency of any raw HID key
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void setupKeyStepMap() {
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for (int i = 0; i < 128; i++) {
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keyStepMap[i] = 0;
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}
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// Implements the "standard" PC keyboard to piano setup
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// https://ux.stackexchange.com/questions/46669/mapping-piano-keys-to-computer-keyboard
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keyStepMap[KeyboardLayout_en_US['a']] = stepForHz(261.6256);
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keyStepMap[KeyboardLayout_en_US['w']] = stepForHz(277.1826);
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keyStepMap[KeyboardLayout_en_US['s']] = stepForHz(293.6648);
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keyStepMap[KeyboardLayout_en_US['e']] = stepForHz(311.1270);
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keyStepMap[KeyboardLayout_en_US['d']] = stepForHz(329.6276);
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keyStepMap[KeyboardLayout_en_US['f']] = stepForHz(349.2282);
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keyStepMap[KeyboardLayout_en_US['t']] = stepForHz(369.9944);
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keyStepMap[KeyboardLayout_en_US['g']] = stepForHz(391.9954);
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keyStepMap[KeyboardLayout_en_US['y']] = stepForHz(415.3047);
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keyStepMap[KeyboardLayout_en_US['h']] = stepForHz(440.0000);
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keyStepMap[KeyboardLayout_en_US['u']] = stepForHz(466.1638);
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keyStepMap[KeyboardLayout_en_US['j']] = stepForHz(493.8833);
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keyStepMap[KeyboardLayout_en_US['k']] = stepForHz(523.2511);
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keyStepMap[KeyboardLayout_en_US['o']] = stepForHz(554.3653);
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keyStepMap[KeyboardLayout_en_US['l']] = stepForHz(587.3295);
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keyStepMap[KeyboardLayout_en_US['p']] = stepForHz(622.2540);
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keyStepMap[KeyboardLayout_en_US[';']] = stepForHz(659.2551);
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keyStepMap[KeyboardLayout_en_US['\'']] = stepForHz(698.4565);
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}
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// We get make/break for every key which lets us hold notes while a key is depressed
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void kb(void *cbdata, int key) {
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bool state = (bool)cbdata;
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if (state && key < 128) {
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// Starting a new note
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for (int i = 0; i < 6; i++) {
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if (osc[i].step == 0) {
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// This one is free
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osc[i].key = key;
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osc[i].pos = 0;
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osc[i].step = keyStepMap[key];
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break;
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}
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}
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} else {
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for (int i = 0; i < 6; i++) {
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if (osc[i].key == (uint32_t)key) {
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osc[i].step = 0;
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break;
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}
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}
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}
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// The HIDKeyStream object converts a key and state into ASCII. HID key IDs do not map 1:1 to ASCII!
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// Write the key and make/break state, then read 1 ASCII char back out.
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keystream.write((uint8_t)key);
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keystream.write((uint8_t)state);
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Serial.printf("Keyboard: %02x %s = '%c'\n", key, state ? "DOWN" : "UP", state ? keystream.read() : '-');
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}
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// Consumer keys are the special media keys on most modern keyboards (mute/etc.)
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void ckb(void *cbdata, int key) {
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bool state = (bool)cbdata;
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Serial.printf("Consumer: %02x %s\n", key, state ? "DOWN" : "UP");
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}
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void setup() {
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Serial.begin();
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delay(3000);
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Serial.printf("Starting HID master, put your device in pairing mode now.\n");
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// Init the sound generator
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precalculateSine();
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silenceOscillators();
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setupKeyStepMap();
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// Setup the HID key to ASCII conversion
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keystream.begin();
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// Init the PWM audio output
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pwm.setStereo(true);
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pwm.setBuffers(16, 64);
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pwm.onTransmit(fill);
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pwm.begin(44100);
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// Mouse buttons and movement reported separately
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hid.onMouseMove(mm);
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hid.onMouseButton(mb);
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// We can use the cbData as a flag to see if we're making or breaking a key
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hid.onKeyDown(kb, (void *)true);
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hid.onKeyUp(kb, (void *)false);
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// Consumer keys are the special function ones like "mute" or "home"
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hid.onConsumerKeyDown(ckb, (void *)true);
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hid.onConsumerKeyUp(ckb, (void *)false);
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hid.begin();
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hid.connectKeyboard();
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// or hid.connectMouse();
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}
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void loop() {
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if (BOOTSEL) {
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while (BOOTSEL) {
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delay(1);
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}
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hid.disconnect();
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hid.clearPairing();
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Serial.printf("Restarting HID master, put your device in pairing mode now.\n");
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hid.connectKeyboard();
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}
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}

‎libraries/BluetoothHIDMaster/keywords.txt

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#######################################
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# Syntax Coloring Map
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#######################################
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#######################################
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# Datatypes (KEYWORD1)
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#######################################
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BluetoothHIDMaster KEYWORD1
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HIDKeyStream KEYWORD1
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#######################################
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# Methods and Functions (KEYWORD2)
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#######################################
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begin KEYWORD2
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end KEYWORD2
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scan KEYWORD2
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scanAsyncDone KEYWORD2
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scanAsyncResult KEYWORD2
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connectKeyboard KEYWORD2
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connectMouse KEYWORD2
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hidConnected KEYWORD2
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onMouseMove KEYWORD2
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onMouseButton KEYWORD2
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onKeyDown KEYWORD2
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onKeyUp KEYWORD2
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onConsumerKeyDown KEYWORD2
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onConsumerKeyUp KEYWORD2
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# BTDeviceInfo
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deviceClass KEYWORD2
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address KEYWORD2
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addressString KEYWORD2
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rssi KEYWORD2
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name KEYWORD2
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#######################################
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# Constants (LITERAL1)
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#######################################

‎libraries/BluetoothHIDMaster/library.properties

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name=BluetoothHIDMaster
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version=1.0
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author=Earle F. Philhower, III <earlephilhower@yahoo.com>
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maintainer=Earle F. Philhower, III <earlephilhower@yahoo.com>
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sentence=Classic Bluetooth HID (Keyboard/Mouse/Joystick) master mode
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paragraph=Classic Bluetooth HID (Keyboard/Mouse/Joystick) master mode
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category=Communication
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url=http://github.com/earlephilhower/arduino-pico
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architectures=rp2040
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dot_a_linkage=true
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depends=BluetoothHCI

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