btstack/platforms/arduino/examples/LEPeripheral/LEPeripheral.ino

// LE Peripheral Example - not working yet
#include <BTstack.h>
#include <SPI.h>

#define GATT_CHARACTERISTIC_TEMP_ID 0

// setup printf
static FILE uartout = {0} ;
static int uart_putchar (char c, FILE *stream) {
    Serial.write(c);
    return 0;
}
static void setup_printf(int baud) {
  Serial.begin(baud);
  fdev_setup_stream (&uartout, uart_putchar, NULL, _FDEV_SETUP_WRITE);
  stdout = &uartout;
}  

void setup() {

  setup_printf(9600);

  // set callbacks
  BTstack.setBLEDeviceConnectedCallback(deviceConnectedCallback);
  BTstack.setBLEDeviceDisconnectedCallback(deviceDisconnectedCallback);
  BTstack.setGATTCharacteristicRead(gattReadCallback);
  BTstack.setGATTCharacteristicWrite(gattWriteCallback);

  // setup GATT Database
  int flags = 0;
  uint8_t * data = NULL;
  uint16_t data_len = 0;
  BTstack.addGATTService(new UUID("B8E06067-62AD-41BA-9231-206AE80AB550"));
  BTstack.addGATTCharacteristic(new UUID("f897177b-aee8-4767-8ecc-cc694fd5fcee"), flags, "string");
  BTstack.addGATTCharacteristic(new UUID("f897177b-aee8-4767-8ecc-cc694fd5fcee"), flags, data, data_len);
  BTstack.addGATTCharacteristicDynamic(new UUID("f897177b-aee8-4767-8ecc-cc694fd5fcee"), flags, GATT_CHARACTERISTIC_TEMP_ID);
  // ..

  BTstack.setup();
}


void loop() {
  BTstack.loop();
}

void deviceConnectedCallback(BLEStatus status, BLEDevice *device) {
  switch (status){
    case BLE_STATUS_OK:
      printf("Device connected!\n");
      break;
    default:
      break;
  }
}

void deviceDisconnectedCallback(BLEDevice * device){
  printf("Disconnected.\n");
}

// ATT Client Read Callback for Dynamic Data
// - if buffer == NULL, don't copy data, just return size of value
// - if buffer != NULL, copy data and return number bytes copied
// @param characteristic_id to be read
// @param buffer 
// @param buffer_size
uint16_t gattReadCallback(uint16_t characteristic_id, uint8_t * buffer, uint16_t buffer_size){
    switch (characteristic_id){
      case GATT_CHARACTERISTIC_TEMP_ID:
        break;
    }
    return 0;
}

// ATT Client Write Callback for Dynamic Data
// @param characteristic_id to be read
// @param buffer 
// @param buffer_size
// @returns 0 if write was ok, ATT_ERROR_INVALID_OFFSET if offset is larger than max buffer
int gattWriteCallback(uint16_t characteristic_id, uint8_t *buffer, uint16_t buffer_size){
    switch (characteristic_id){
    }
    return 0;
}