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# 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.
#
# Work-in-progress demo of implementing bonding and passkey auth.
#
# This example demonstrates the low-level bluetooth module. For most
# applications, we recommend using the higher-level aioble library, which
# includes an implementation of the secret store. See
# https://github.com/micropython/micropython-lib/tree/master/micropython/bluetooth/aioble
import bluetooth
import random
import struct
import time
import json
import binascii
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)
_IRQ_ENCRYPTION_UPDATE = const(28)
_IRQ_PASSKEY_ACTION = const(31)
_IRQ_GET_SECRET = const(29)
_IRQ_SET_SECRET = const(30)
_FLAG_READ = const(0x0002)
_FLAG_NOTIFY = const(0x0010)
_FLAG_INDICATE = const(0x0020)
_FLAG_READ_ENCRYPTED = const(0x0200)
# 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 | _FLAG_READ_ENCRYPTED,
)
_ENV_SENSE_SERVICE = (
_ENV_SENSE_UUID,
(_TEMP_CHAR,),
)
# org.bluetooth.characteristic.gap.appearance.xml
_ADV_APPEARANCE_GENERIC_THERMOMETER = const(768)
_IO_CAPABILITY_DISPLAY_ONLY = const(0)
_IO_CAPABILITY_DISPLAY_YESNO = const(1)
_IO_CAPABILITY_KEYBOARD_ONLY = const(2)
_IO_CAPABILITY_NO_INPUT_OUTPUT = const(3)
_IO_CAPABILITY_KEYBOARD_DISPLAY = const(4)
_PASSKEY_ACTION_INPUT = const(2)
_PASSKEY_ACTION_DISP = const(3)
_PASSKEY_ACTION_NUMCMP = const(4)
class BLETemperature:
def __init__(self, ble, name="mpy-temp"):
self._ble = ble
self._load_secrets()
self._ble.irq(self._irq)
self._ble.config(bond=True)
self._ble.config(le_secure=True)
self._ble.config(mitm=True)
self._ble.config(io=_IO_CAPABILITY_DISPLAY_YESNO)
self._ble.active(True)
self._ble.config(addr_mode=2)
((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)
self._save_secrets()
# Start advertising again to allow a new connection.
self._advertise()
elif event == _IRQ_ENCRYPTION_UPDATE:
conn_handle, encrypted, authenticated, bonded, key_size = data
print("encryption update", conn_handle, encrypted, authenticated, bonded, key_size)
elif event == _IRQ_PASSKEY_ACTION:
conn_handle, action, passkey = data
print("passkey action", conn_handle, action, passkey)
if action == _PASSKEY_ACTION_NUMCMP:
accept = int(input("accept? "))
self._ble.gap_passkey(conn_handle, action, accept)
elif action == _PASSKEY_ACTION_DISP:
print("displaying 123456")
self._ble.gap_passkey(conn_handle, action, 123456)
elif action == _PASSKEY_ACTION_INPUT:
print("prompting for passkey")
passkey = int(input("passkey? "))
self._ble.gap_passkey(conn_handle, action, passkey)
else:
print("unknown action")
elif event == _IRQ_GATTS_INDICATE_DONE:
conn_handle, value_handle, status = data
elif event == _IRQ_SET_SECRET:
sec_type, key, value = data
key = sec_type, bytes(key)
value = bytes(value) if value else None
print("set secret:", key, value)
if value is None:
if key in self._secrets:
del self._secrets[key]
return True
else:
return False
else:
self._secrets[key] = value
return True
elif event == _IRQ_GET_SECRET:
sec_type, index, key = data
print("get secret:", sec_type, index, bytes(key) if key else None)
if key is None:
i = 0
for (t, _key), value in self._secrets.items():
if t == sec_type:
if i == index:
return value
i += 1
return None
else:
key = sec_type, bytes(key)
return self._secrets.get(key, None)
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.config(addr_mode=2)
self._ble.gap_advertise(interval_us, adv_data=self._payload)
def _load_secrets(self):
self._secrets = {}
try:
with open("secrets.json", "r") as f:
entries = json.load(f)
for sec_type, key, value in entries:
self._secrets[sec_type, binascii.a2b_base64(key)] = binascii.a2b_base64(value)
except:
print("no secrets available")
def _save_secrets(self):
try:
with open("secrets.json", "w") as f:
json_secrets = [
(sec_type, binascii.b2a_base64(key), binascii.b2a_base64(value))
for (sec_type, key), value in self._secrets.items()
]
json.dump(json_secrets, f)
except:
print("failed to save secrets")
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()
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