manuelbl/README.md

## README.md

      
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    ESP32 as Bluetooth Keyboard
With its built-in Bluetooth capabilities, the ESP32 can act as a Bluetooth keyboard. The below code is a minimal example of how to achieve it. It will generate the key strokes for a message whenever a button attached to the ESP32 is pressed.
For the example setup, a momentary button should be connected to pin 2 and to ground. Pin 2 will be configured as an input with pull-up.
In order to receive the message, add the ESP32 as a Bluetooth keyboard of your computer or mobile phone:

Go to your computers/phones settings
Ensure Bluetooth is turned on
Scan for Bluetooth devices
Connect to the device called "ESP32 Keyboard"
Open an empty document in a text editor
Press the button attached to the ESP32

The code has been written for the Arduino framework. I recommend using PlatformIO for development as it is far superior to the Arduino IDE while still taking full advantage of the Arduino ecosystem (libraries, support etc.)

  
## main.cpp
/*
 * Sample program for ESP32 acting as a Bluetooth keyboard
 *
 * Copyright (c) 2019 Manuel Bl
 *
 * Licensed under MIT License
 * https://opensource.org/licenses/MIT
 */

//
// This program lets an ESP32 act as a keyboard connected via Bluetooth.
// When a button attached to the ESP32 is pressed, it will generate the key strokes for a message.
//
// For the setup, a momentary button should be connected to pin 2 and to ground.
// Pin 2 will be configured as an input with pull-up.
//
// In order to receive the message, add the ESP32 as a Bluetooth keyboard of your computer
// or mobile phone:
//
// 1. Go to your computers/phones settings
// 2. Ensure Bluetooth is turned on
// 3. Scan for Bluetooth devices
// 4. Connect to the device called "ESP32 Keyboard"
// 5. Open an empty document in a text editor
// 6. Press the button attached to the ESP32

#define US_KEYBOARD 1

#include <Arduino.h>
#include "BLEDevice.h"
#include "BLEHIDDevice.h"
#include "HIDTypes.h"
#include "HIDKeyboardTypes.h"


// Change the below values if desired
#define BUTTON_PIN 2
#define MESSAGE "Hello from ESP32\n"
#define DEVICE_NAME "ESP32 Keyboard"


// Forward declarations
void bluetoothTask(void*);
void typeText(const char* text);


bool isBleConnected = false;


void setup() {
    Serial.begin(115200);

    // configure pin for button
    pinMode(BUTTON_PIN, INPUT_PULLUP);

    // start Bluetooth task
    xTaskCreate(bluetoothTask, "bluetooth", 20000, NULL, 5, NULL);
}


void loop() {
    if (isBleConnected && digitalRead(BUTTON_PIN) == LOW) {
        // button has been pressed: type message
        Serial.println(MESSAGE);
        typeText(MESSAGE);
    }

    delay(100);
}


// 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);
    }
}
	/*
	* Sample program for ESP32 acting as a Bluetooth keyboard
	*
	* Copyright (c) 2019 Manuel Bl
	*
	* Licensed under MIT License
	* https://opensource.org/licenses/MIT
	*/

	//
	// This program lets an ESP32 act as a keyboard connected via Bluetooth.
	// When a button attached to the ESP32 is pressed, it will generate the key strokes for a message.
	//
	// For the setup, a momentary button should be connected to pin 2 and to ground.
	// Pin 2 will be configured as an input with pull-up.
	//
	// In order to receive the message, add the ESP32 as a Bluetooth keyboard of your computer
	// or mobile phone:
	//
	// 1. Go to your computers/phones settings
	// 2. Ensure Bluetooth is turned on
	// 3. Scan for Bluetooth devices
	// 4. Connect to the device called "ESP32 Keyboard"
	// 5. Open an empty document in a text editor
	// 6. Press the button attached to the ESP32

	#define US_KEYBOARD 1

	#include <Arduino.h>
	#include "BLEDevice.h"
	#include "BLEHIDDevice.h"
	#include "HIDTypes.h"
	#include "HIDKeyboardTypes.h"


	// Change the below values if desired
	#define BUTTON_PIN 2
	#define MESSAGE "Hello from ESP32\n"
	#define DEVICE_NAME "ESP32 Keyboard"


	// Forward declarations
	void bluetoothTask(void*);
	void typeText(const char* text);


	bool isBleConnected = false;


	void setup() {
	Serial.begin(115200);

	// configure pin for button
	pinMode(BUTTON_PIN, INPUT_PULLUP);

	// start Bluetooth task
	xTaskCreate(bluetoothTask, "bluetooth", 20000, NULL, 5, NULL);
	}


	void loop() {
	if (isBleConnected && digitalRead(BUTTON_PIN) == LOW) {
	// button has been pressed: type message
	Serial.println(MESSAGE);
	typeText(MESSAGE);
	}

	delay(100);
	}


	// 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);
	}
	}