Taiko-Drum-Controller-Arduino/ESP32/keyboard.h

// Bluetooth keyboard implemetation by manuelbl:
// https://gist.github.com/manuelbl/66f059effc8a7be148adb1f104666467

#include "BLEDevice.h"
#include "BLEHIDDevice.h"
#include "HIDKeyboardTypes.h"
#include "HIDTypes.h"

#define DEVICE_NAME "ESP32 Taiko Controller"

bool isBleConnected = false;

// Message (report) sent when a key is pressed or released
struct InputReport {
    uint8_t modifiers;       // bitmask: CTRL = 1, SHIFT = 2, ALT = 4
    uint8_t reserved;        // must be 0
    uint8_t pressedKeys[6];  // up to six concurrenlty pressed keys
};

// Message (report) received when an LED's state changed
struct OutputReport {
    uint8_t leds;  // bitmask: num lock = 1, caps lock = 2, scroll lock = 4,
                   // compose = 8, kana = 16
};

// The report map describes the HID device (a keyboard in this case) and
// the messages (reports in HID terms) sent and received.
static const uint8_t REPORT_MAP[] = {
    USAGE_PAGE(1),
    0x01,  // Generic Desktop Controls
    USAGE(1),
    0x06,  // Keyboard
    COLLECTION(1),
    0x01,  // Application
    REPORT_ID(1),
    0x01,  //   Report ID (1)
    USAGE_PAGE(1),
    0x07,  //   Keyboard/Keypad
    USAGE_MINIMUM(1),
    0xE0,  //   Keyboard Left Control
    USAGE_MAXIMUM(1),
    0xE7,  //   Keyboard Right Control
    LOGICAL_MINIMUM(1),
    0x00,  //   Each bit is either 0 or 1
    LOGICAL_MAXIMUM(1),
    0x01,
    REPORT_COUNT(1),
    0x08,  //   8 bits for the modifier keys
    REPORT_SIZE(1),
    0x01,
    HIDINPUT(1),
    0x02,  //   Data, Var, Abs
    REPORT_COUNT(1),
    0x01,  //   1 byte (unused)
    REPORT_SIZE(1),
    0x08,
    HIDINPUT(1),
    0x01,  //   Const, Array, Abs
    REPORT_COUNT(1),
    0x06,  //   6 bytes (for up to 6 concurrently pressed keys)
    REPORT_SIZE(1),
    0x08,
    LOGICAL_MINIMUM(1),
    0x00,
    LOGICAL_MAXIMUM(1),
    0x65,  //   101 keys
    USAGE_MINIMUM(1),
    0x00,
    USAGE_MAXIMUM(1),
    0x65,
    HIDINPUT(1),
    0x00,  //   Data, Array, Abs
    REPORT_COUNT(1),
    0x05,  //   5 bits (Num lock, Caps lock, Scroll lock, Compose, Kana)
    REPORT_SIZE(1),
    0x01,
    USAGE_PAGE(1),
    0x08,  //   LEDs
    USAGE_MINIMUM(1),
    0x01,  //   Num Lock
    USAGE_MAXIMUM(1),
    0x05,  //   Kana
    LOGICAL_MINIMUM(1),
    0x00,
    LOGICAL_MAXIMUM(1),
    0x01,
    HIDOUTPUT(1),
    0x02,  //   Data, Var, Abs
    REPORT_COUNT(1),
    0x01,  //   3 bits (Padding)
    REPORT_SIZE(1),
    0x03,
    HIDOUTPUT(1),
    0x01,              //   Const, Array, Abs
    END_COLLECTION(0)  // End application collection
};

BLEHIDDevice* hid;
BLECharacteristic* input;
BLECharacteristic* output;

const InputReport NO_KEY_PRESSED = {};

/*
 * Callbacks related to BLE connection
 */
class BleKeyboardCallbacks : public BLEServerCallbacks {
    void onConnect(BLEServer* server) {
        isBleConnected = true;

        // Allow notifications for characteristics
        BLE2902* cccDesc =
            (BLE2902*)input->getDescriptorByUUID(BLEUUID((uint16_t)0x2902));
        cccDesc->setNotifications(true);

        Serial.println("Client has connected");
    }

    void onDisconnect(BLEServer* server) {
        isBleConnected = false;

        // Disallow notifications for characteristics
        BLE2902* cccDesc =
            (BLE2902*)input->getDescriptorByUUID(BLEUUID((uint16_t)0x2902));
        cccDesc->setNotifications(false);

        Serial.println("Client has disconnected");
    }
};

/*
 * Called when the client (computer, smart phone) wants to turn on or off
 * the LEDs in the keyboard.
 *
 * bit 0 - NUM LOCK
 * bit 1 - CAPS LOCK
 * bit 2 - SCROLL LOCK
 */
class OutputCallbacks : public BLECharacteristicCallbacks {
    void onWrite(BLECharacteristic* characteristic) {
        OutputReport* report = (OutputReport*)characteristic->getData();
        Serial.print("LED state: ");
        Serial.print((int)report->leds);
        Serial.println();
    }
};

void bluetoothTask(void*) {
    // initialize the device
    BLEDevice::init(DEVICE_NAME);
    BLEServer* server = BLEDevice::createServer();
    server->setCallbacks(new BleKeyboardCallbacks());

    // create an HID device
    hid = new BLEHIDDevice(server);
    input = hid->inputReport(1);    // report ID
    output = hid->outputReport(1);  // report ID
    output->setCallbacks(new OutputCallbacks());

    // set manufacturer name
    hid->manufacturer()->setValue("Maker Community");
    // set USB vendor and product ID
    hid->pnp(0x02, 0xe502, 0xa111, 0x0210);
    // information about HID device: device is not localized, device can be
    // connected
    hid->hidInfo(0x00, 0x02);

    // Security: device requires bonding
    BLESecurity* security = new BLESecurity();
    security->setAuthenticationMode(ESP_LE_AUTH_BOND);

    // set report map
    hid->reportMap((uint8_t*)REPORT_MAP, sizeof(REPORT_MAP));
    hid->startServices();

    // set battery level to 100%
    hid->setBatteryLevel(100);

    // advertise the services
    BLEAdvertising* advertising = server->getAdvertising();
    advertising->setAppearance(HID_KEYBOARD);
    advertising->addServiceUUID(hid->hidService()->getUUID());
    advertising->addServiceUUID(hid->deviceInfo()->getUUID());
    advertising->addServiceUUID(hid->batteryService()->getUUID());
    advertising->start();

    Serial.println("BLE ready");
    delay(portMAX_DELAY);
};

void typeText(const char* text) {
    int len = strlen(text);
    for (int i = 0; i < len; i++) {
        // translate character to key combination
        uint8_t val = (uint8_t)text[i];
        if (val > KEYMAP_SIZE)
            continue;  // character not available on keyboard - skip
        KEYMAP map = keymap[val];

        // create input report
        InputReport report = {.modifiers = map.modifier,
                              .reserved = 0,
                              .pressedKeys = {map.usage, 0, 0, 0, 0, 0}};

        // send the input report
        input->setValue((uint8_t*)&report, sizeof(report));
        input->notify();

        delay(5);

        // release all keys between two characters; otherwise two identical
        // consecutive characters are treated as just one key press
        input->setValue((uint8_t*)&NO_KEY_PRESSED, sizeof(NO_KEY_PRESSED));
        input->notify();

        delay(5);
    }
}

void typeChar(char c) {
    uint8_t val = (uint8_t)c;
    KEYMAP map = keymap[val];
    InputReport report = {.modifiers = map.modifier,
                          .reserved = 0,
                          .pressedKeys = {map.usage, 0, 0, 0, 0, 0}};
    input->setValue((uint8_t*)&report, sizeof(report));
    input->notify();
    delay(1);
    input->setValue((uint8_t*)&NO_KEY_PRESSED, sizeof(NO_KEY_PRESSED));
    input->notify();
    delay(1);
}