new_contents: # This example demonstrates a simple temperature sensor peripheral.
  #
  # The sensor's local value updates every second, and it will notify
  # any connected central every 10 seconds.
  
  import bluetooth
  import random
  import struct
  import time
  from ble_advertising import advertising_payload
  
  from micropython import const
  
  _IRQ_CENTRAL_CONNECT = const(1)
  _IRQ_CENTRAL_DISCONNECT = const(2)
  _IRQ_GATTS_INDICATE_DONE = const(20)
  
  _FLAG_READ = const(0x0002)
  _FLAG_NOTIFY = const(0x0010)
  _FLAG_INDICATE = const(0x0020)
  
  # org.bluetooth.service.environmental_sensing
  _ENV_SENSE_UUID = bluetooth.UUID(0x181A)
  # org.bluetooth.characteristic.temperature
  _TEMP_CHAR = (
      bluetooth.UUID(0x2A6E),
      _FLAG_READ | _FLAG_NOTIFY | _FLAG_INDICATE,
  )
  _ENV_SENSE_SERVICE = (
      _ENV_SENSE_UUID,
      (_TEMP_CHAR,),
  )
  
  # org.bluetooth.characteristic.gap.appearance.xml
  _ADV_APPEARANCE_GENERIC_THERMOMETER = const(768)
  
  
  class BLETemperature:
      def __init__(self, ble, name="PORTENTA_BLE"):
          self._ble = ble
          self._ble.active(True)
          self._ble.irq(self._irq)
          ((self._handle,),) = self._ble.gatts_register_services((_ENV_SENSE_SERVICE,))
          self._connections = set()
          self._payload = advertising_payload(
              name=name, services=[_ENV_SENSE_UUID], appearance=_ADV_APPEARANCE_GENERIC_THERMOMETER
          )
          self._advertise()
  
      def _irq(self, event, data):
          # Track connections so we can send notifications.
          if event == _IRQ_CENTRAL_CONNECT:
              conn_handle, _, _ = data
              self._connections.add(conn_handle)
          elif event == _IRQ_CENTRAL_DISCONNECT:
              conn_handle, _, _ = data
              self._connections.remove(conn_handle)
              # Start advertising again to allow a new connection.
              self._advertise()
          elif event == _IRQ_GATTS_INDICATE_DONE:
              conn_handle, value_handle, status = data
  
      def set_temperature(self, temp_deg_c, notify=False, indicate=False):
          # Data is sint16 in degrees Celsius with a resolution of 0.01 degrees Celsius.
          # Write the local value, ready for a central to read.
          self._ble.gatts_write(self._handle, struct.pack("<h", int(temp_deg_c * 100)))
          if notify or indicate:
              for conn_handle in self._connections:
                  if notify:
                      # Notify connected centrals.
                      self._ble.gatts_notify(conn_handle, self._handle)
                  if indicate:
                      # Indicate connected centrals.
                      self._ble.gatts_indicate(conn_handle, self._handle)
  
      def _advertise(self, interval_us=500000):
          self._ble.gap_advertise(interval_us, adv_data=self._payload)
  
  
  def demo():
      ble = bluetooth.BLE()
      temp = BLETemperature(ble)
  
      t = 25
      i = 0
  
      while True:
          # Write every second, notify every 10 seconds.
          i = (i + 1) % 10
          temp.set_temperature(t, notify=i == 0, indicate=False)
          # Random walk the temperature.
          t += random.uniform(-0.5, 0.5)
          time.sleep_ms(1000)
  
  
  if __name__ == "__main__":
      demo()
  
subject: Add BLE example.