BLE_SimpleChat example for Readbear BLE NANO adapted to send potentiometer.

BLE_Potentiometer_Chat.ino

#include <BLE_API.h>

#define DEVICE_NAME          "PotentiometerToChat"
#define TXRX_BUF_LEN         20

#define DEVICE_ID            0xFF

BLE                          ble;


const int SOFT_POT_PIN = A3; // Pin connected to softpot wiper

const int GRAPH_LENGTH = 40; // Length of line graph


// The uuid of service and characteristics
static const uint8_t service1_uuid[]         = {0x71, 0x3D, 0, 0, 0x50, 0x3E, 0x4C, 0x75, 0xBA, 0x94, 0x31, 0x48, 0xF1, 0x8D, 0x94, 0x1E};
static const uint8_t service1_chars1_uuid[]  = {0x71, 0x3D, 0, 3, 0x50, 0x3E, 0x4C, 0x75, 0xBA, 0x94, 0x31, 0x48, 0xF1, 0x8D, 0x94, 0x1E};
static const uint8_t service1_chars2_uuid[]  = {0x71, 0x3D, 0, 2, 0x50, 0x3E, 0x4C, 0x75, 0xBA, 0x94, 0x31, 0x48, 0xF1, 0x8D, 0x94, 0x1E};
static const uint8_t uart_base_uuid_rev[]    = {0x1E, 0x94, 0x8D, 0xF1, 0x48, 0x31, 0x94, 0xBA, 0x75, 0x4C, 0x3E, 0x50, 0, 0, 0x3D, 0x71};

uint8_t chars1_value[TXRX_BUF_LEN] = {0};
uint8_t chars2_value[TXRX_BUF_LEN] = {0};

// Create characteristic and service
GattCharacteristic  characteristic1(service1_chars1_uuid, chars1_value, 1, TXRX_BUF_LEN, GattCharacteristic::BLE_GATT_CHAR_PROPERTIES_WRITE | GattCharacteristic::BLE_GATT_CHAR_PROPERTIES_WRITE_WITHOUT_RESPONSE );
GattCharacteristic  characteristic2(service1_chars2_uuid, chars2_value, 1, TXRX_BUF_LEN, GattCharacteristic::BLE_GATT_CHAR_PROPERTIES_NOTIFY | GattCharacteristic::BLE_GATT_CHAR_PROPERTIES_READ);
GattCharacteristic *uartChars[] = {&characteristic1, &characteristic2};
GattService         uartService(service1_uuid, uartChars, sizeof(uartChars) / sizeof(GattCharacteristic *));


void disconnectionCallBack(const Gap::DisconnectionCallbackParams_t *params) {
  ble.startAdvertising();
}

void gattServerWriteCallBack(const GattWriteCallbackParams *Handler) {
  uint8_t buf[TXRX_BUF_LEN];
  uint16_t bytesRead, index;

  Serial.println("Write Handle : ");
  if (Handler->handle == characteristic1.getValueAttribute().getHandle()) {
    ble.readCharacteristicValue(characteristic1.getValueAttribute().getHandle(), buf, &bytesRead);
    for(index=0; index<bytesRead; index++)
    {
        Serial.print(buf[index], HEX);
    }
//    write_handle();
  }
}


void setup() {
  // put your setup code here, to run once
  Serial.begin(9600);
  Serial.println("Start ");

  // ticker_task1.attach(sendMessage, 2);

  
  ble.init();
  ble.onDisconnection(disconnectionCallBack);
  ble.onDataWritten(gattServerWriteCallBack);
  // setup adv_data and srp_data
  ble.accumulateAdvertisingPayload(GapAdvertisingData::BREDR_NOT_SUPPORTED);
  ble.accumulateAdvertisingPayload(GapAdvertisingData::SHORTENED_LOCAL_NAME,
                                   (const uint8_t *)DEVICE_NAME, sizeof(DEVICE_NAME) - 1);
  ble.accumulateAdvertisingPayload(GapAdvertisingData::COMPLETE_LIST_128BIT_SERVICE_IDS,
                                   (const uint8_t *)uart_base_uuid_rev, sizeof(uart_base_uuid_rev));
  // set adv_type
  ble.setAdvertisingType(GapAdvertisingParams::ADV_CONNECTABLE_UNDIRECTED);
  // add service
  ble.addService(uartService);
  // set device name
  ble.setDeviceName((const uint8_t *)DEVICE_NAME);
  // set tx power,valid values are -40, -20, -16, -12, -8, -4, 0, 4
  ble.setTxPower(4);
  // set adv_interval, 100ms in multiples of 0.625ms.
  ble.setAdvertisingInterval(160);
  // set adv_timeout, in seconds
  ble.setAdvertisingTimeout(0);
  
  ble.startAdvertising();
  Serial.println("start advertising ");
}



void loop() {
  // put your main code here, to run repeatedly:
  ble.waitForEvent();

   // Read in the soft pot's ADC value
  int softPotADC = analogRead(SOFT_POT_PIN);
  // Map the 0-1023 value to 0-40. On testing the actual values are between 350 and 700
  int softPotPosition = map(softPotADC, 350, 700, 0, GRAPH_LENGTH);
  if (softPotPosition>0)
    uint8_t buf[2] = {softPotPosition, (softPotPosition >> 8)}; ble.updateCharacteristicValue(characteristic2.getValueAttribute().getHandle(), buf, sizeof(buf) - 1 );

  delay(500);
}