Try Beacon- It works! 🙂

#include <ArduinoBLE.h>

void setup()
{
  Serial.begin(9600);
  BLE.setLocalName("testBeacon");
  BLE.begin();
  // start advertising
  BLE.advertise();
}

void loop()
{
  const int DATA_SIZE = 2;
  uint8_t data[DATA_SIZE];


    data[0] = ( uint8_t ) 19;

    BLE.stopAdvertise();
    BLE.setManufacturerData( data, DATA_SIZE );
    BLE.advertise();

}