My former post show steps to MicroPython bluetooth (BLE) exampls, run on ESP32-C3. It's modified to send and receive command to control onboard LED
remotely.
ble_simple_peripheral_LED.py (modified from ble_simple_peripheral.py) run on AI-Thinker NodeMCU ESP-C3-32S-Kit, act to be BLE Peripheral.
ble_simple_central_button.py
(modified from ble_simple_central.py) run on Espressif ESP32-C3-DevKitM-1, act to be BLE Central.
Both
flashed with MicroPython v1.19.1 frameware. ble_advertising.py have to be saved on both central/peripheral MicroPython device.
Once
connected, user pressed central's onboard button to send command
to peripheral via BLE UART, to toggle peripheral onboard LED.
In
peripheral side, turn ON/OFF onboard LED according to received command, and
send back the command to central, to control central's onboard LED.
Once
central receive command, turn ON/OFF onboard LED accordingly.
related:
~ MicroPython/NodeMCU ESP-C3-32S-Kit to control onboard LEDs
~ MicroPython/ESP32-C3-DevKitM-1 exercise: onboard BOOT button, and RGB LED
(Neopixel)
ble_simple_peripheral_LED.py
"""
MicroPython(v1.19.1) exercise
run on AI-Thinker NodeMCU ESP-C3-32S-Kit
act as BLE UART periperhal.
Receive command from central, turn on/off onboard LED,
and send back the command to central.
Modified from MicroPython ble_simple_peripheral.py example
https://github.com/micropython/micropython/
blob/master/examples/bluetooth/ble_simple_central.py
"""
# This example demonstrates a UART periperhal.
import bluetooth
import random
import struct
import time
from ble_advertising import advertising_payload
from machine import Pin
from micropython import const
CMD_LEDON = b'LEDON\r\n'
CMD_LEDOFF = b'LEDOFF\r\n'
# NodeMCU ESP-C3-32S-Kit onboard LEDs assignment
pinR = Pin(3, Pin.OUT)
pinG = Pin(4, Pin.OUT)
pinB = Pin(5, Pin.OUT)
_IRQ_CENTRAL_CONNECT = const(1)
_IRQ_CENTRAL_DISCONNECT = const(2)
_IRQ_GATTS_WRITE = const(3)
_FLAG_READ = const(0x0002)
_FLAG_WRITE_NO_RESPONSE = const(0x0004)
_FLAG_WRITE = const(0x0008)
_FLAG_NOTIFY = const(0x0010)
_UART_UUID = bluetooth.UUID(
"6E400001-B5A3-F393-E0A9-E50E24DCCA9E")
_UART_TX = (
bluetooth.UUID(
"6E400003-B5A3-F393-E0A9-E50E24DCCA9E"),
_FLAG_READ | _FLAG_NOTIFY,
)
_UART_RX = (
bluetooth.UUID(
"6E400002-B5A3-F393-E0A9-E50E24DCCA9E"),
_FLAG_WRITE | _FLAG_WRITE_NO_RESPONSE,
)
_UART_SERVICE = (
_UART_UUID,
(_UART_TX, _UART_RX),
)
class BLESimplePeripheral:
def __init__(self, ble, name="mpy-uart"):
self._ble = ble
self._ble.active(True)
self._ble.irq(self._irq)
((self._handle_tx,
self._handle_rx),) \
= self._ble.gatts_register_services(
(_UART_SERVICE,))
self._connections = set()
self._write_callback = None
self._payload = \
advertising_payload(
name=name, services=[_UART_UUID])
self._advertise()
def _irq(self, event, data):
# Track connections so we can send notifications.
if event == _IRQ_CENTRAL_CONNECT:
conn_handle, _, _ = data
print("New connection", conn_handle)
self._connections.add(conn_handle)
elif event == _IRQ_CENTRAL_DISCONNECT:
conn_handle, _, _ = data
print("Disconnected", conn_handle)
self._connections.remove(conn_handle)
# Start advertising again to allow a new connection.
self._advertise()
elif event == _IRQ_GATTS_WRITE:
conn_handle, value_handle = data
value = self._ble.gatts_read(value_handle)
if (value_handle == self._handle_rx and
self._write_callback):
self._write_callback(value)
def send(self, data):
for conn_handle in self._connections:
self._ble.gatts_notify(conn_handle,
self._handle_tx,
data)
def is_connected(self):
return len(self._connections) > 0
def _advertise(self, interval_us=500000):
print("Starting advertising")
self._ble.gap_advertise(interval_us,
adv_data=self._payload)
def on_write(self, callback):
self._write_callback = callback
def Turn_LED(val):
pinR.value(val)
pinG.value(val)
pinB.value(val)
def demo():
ble = bluetooth.BLE()
p = BLESimplePeripheral(ble)
def on_rx(v):
# command received from central,
# turn ON/OFF LED accoringly,
# and send back the command to centrol.
print("RX", v)
if v == CMD_LEDON:
Turn_LED(1)
print("command received: ", CMD_LEDON)
p.send("from peripheral:")
p.send(CMD_LEDON)
elif v == CMD_LEDOFF:
Turn_LED(0)
print("command received: ", CMD_LEDOFF)
p.send("from peripheral:")
p.send(CMD_LEDOFF)
p.on_write(on_rx)
i = 0
while True:
"""
if p.is_connected():
# Short burst of queued notifications.
for _ in range(3):
data = str(i) + "_"
print("TX", data)
p.send(data)
i += 1
"""
time.sleep_ms(100)
if __name__ == "__main__":
demo()
ble_simple_central_button.py
"""
MicroPython(v1.19.1) exercise
run on Espressif ESP32-C3-DevKitM-1
act as BLE UART central.
Detect onboard BOOT button,
send command to peripheral to toggle peripheral onboard LED.
and receive command from peripheral, turn on/off onboard.
* No debouncing for BOOT button detection here.
Modified from MicroPython ble_simple_central.py example
https://github.com/micropython/micropython/
blob/master/examples/bluetooth/ble_simple_peripheral.py
"""
# This example finds and connects to a peripheral running the
# UART service (e.g. ble_simple_peripheral.py).
import bluetooth
import random
import struct
import time
import micropython
import machine
import neopixel
from ble_advertising import decode_services, decode_name
from micropython import const
CMD_LEDON = b'LEDON\r\n'
CMD_LEDOFF = b'LEDOFF\r\n'
button_BOOT = machine.Pin(9,
machine.Pin.IN,
machine.Pin.PULL_UP)
np = neopixel.NeoPixel(machine.Pin(8), 1)
# To turn OFF peripheral LED in first power-up
current_led_val = True
root_button_pressed = True
# Turn OFF onboard RGB
np[0] = (0, 0, 0)
np.write()
def boot_pressed_handler(pin):
global root_button_pressed
root_button_pressed = True
button_BOOT.irq(trigger=machine.Pin.IRQ_FALLING,
handler=boot_pressed_handler)
_IRQ_CENTRAL_CONNECT = const(1)
_IRQ_CENTRAL_DISCONNECT = const(2)
_IRQ_GATTS_WRITE = const(3)
_IRQ_GATTS_READ_REQUEST = const(4)
_IRQ_SCAN_RESULT = const(5)
_IRQ_SCAN_DONE = const(6)
_IRQ_PERIPHERAL_CONNECT = const(7)
_IRQ_PERIPHERAL_DISCONNECT = const(8)
_IRQ_GATTC_SERVICE_RESULT = const(9)
_IRQ_GATTC_SERVICE_DONE = const(10)
_IRQ_GATTC_CHARACTERISTIC_RESULT = const(11)
_IRQ_GATTC_CHARACTERISTIC_DONE = const(12)
_IRQ_GATTC_DESCRIPTOR_RESULT = const(13)
_IRQ_GATTC_DESCRIPTOR_DONE = const(14)
_IRQ_GATTC_READ_RESULT = const(15)
_IRQ_GATTC_READ_DONE = const(16)
_IRQ_GATTC_WRITE_DONE = const(17)
_IRQ_GATTC_NOTIFY = const(18)
_IRQ_GATTC_INDICATE = const(19)
_ADV_IND = const(0x00)
_ADV_DIRECT_IND = const(0x01)
_ADV_SCAN_IND = const(0x02)
_ADV_NONCONN_IND = const(0x03)
_UART_SERVICE_UUID = bluetooth.UUID(
"6E400001-B5A3-F393-E0A9-E50E24DCCA9E")
_UART_RX_CHAR_UUID = bluetooth.UUID(
"6E400002-B5A3-F393-E0A9-E50E24DCCA9E")
_UART_TX_CHAR_UUID = bluetooth.UUID(
"6E400003-B5A3-F393-E0A9-E50E24DCCA9E")
class BLESimpleCentral:
def __init__(self, ble):
self._ble = ble
self._ble.active(True)
self._ble.irq(self._irq)
self._reset()
def _reset(self):
# Cached name and address from a successful scan.
self._name = None
self._addr_type = None
self._addr = None
# Callbacks for completion of various operations.
# These reset back to None after being invoked.
self._scan_callback = None
self._conn_callback = None
self._read_callback = None
# Persistent callback for when new data is
# notified from the device.
self._notify_callback = None
# Connected device.
self._conn_handle = None
self._start_handle = None
self._end_handle = None
self._tx_handle = None
self._rx_handle = None
def _irq(self, event, data):
if event == _IRQ_SCAN_RESULT:
addr_type, addr, adv_type, rssi, adv_data = data
if (adv_type in (_ADV_IND, _ADV_DIRECT_IND) and
_UART_SERVICE_UUID in decode_services(adv_data)):
# Found a potential device, remember it
# and stop scanning.
self._addr_type = addr_type
self._addr = bytes(
addr
) # Note: addr buffer is owned by caller so
# need to copy it.
self._name = decode_name(adv_data) or "?"
self._ble.gap_scan(None)
elif event == _IRQ_SCAN_DONE:
if self._scan_callback:
if self._addr:
# Found a device during the scan
# (and the scan was explicitly stopped).
self._scan_callback(self._addr_type,
self._addr,
self._name)
self._scan_callback = None
else:
# Scan timed out.
self._scan_callback(None, None, None)
elif event == _IRQ_PERIPHERAL_CONNECT:
# Connect successful.
conn_handle, addr_type, addr = data
if addr_type == self._addr_type and addr == self._addr:
self._conn_handle = conn_handle
self._ble.gattc_discover_services(self._conn_handle)
elif event == _IRQ_PERIPHERAL_DISCONNECT:
# Disconnect (either initiated by us or the remote end).
conn_handle, _, _ = data
if conn_handle == self._conn_handle:
# If it was initiated by us, it'll already be reset.
self._reset()
elif event == _IRQ_GATTC_SERVICE_RESULT:
# Connected device returned a service.
conn_handle, start_handle, end_handle, uuid = data
print("service", data)
if conn_handle == self._conn_handle and uuid == _UART_SERVICE_UUID:
self._start_handle, self._end_handle = start_handle, end_handle
elif event == _IRQ_GATTC_SERVICE_DONE:
# Service query complete.
if self._start_handle and self._end_handle:
self._ble.gattc_discover_characteristics(
self._conn_handle,
self._start_handle,
self._end_handle
)
else:
print("Failed to find uart service.")
elif event == _IRQ_GATTC_CHARACTERISTIC_RESULT:
# Connected device returned a characteristic.
conn_handle, def_handle, value_handle, properties, uuid = data
if (conn_handle == self._conn_handle and
uuid == _UART_RX_CHAR_UUID):
self._rx_handle = value_handle
if (conn_handle == self._conn_handle and
uuid == _UART_TX_CHAR_UUID):
self._tx_handle = value_handle
elif event == _IRQ_GATTC_CHARACTERISTIC_DONE:
# Characteristic query complete.
if self._tx_handle is not None and self._rx_handle is not None:
# We've finished connecting and discovering device,
# fire the connect callback.
if self._conn_callback:
self._conn_callback()
else:
print("Failed to find uart rx characteristic.")
elif event == _IRQ_GATTC_WRITE_DONE:
conn_handle, value_handle, status = data
print("TX complete")
elif event == _IRQ_GATTC_NOTIFY:
conn_handle, value_handle, notify_data = data
if (conn_handle == self._conn_handle
and value_handle == self._tx_handle):
if self._notify_callback:
self._notify_callback(notify_data)
# Returns true if we've successfully connected and
# discovered characteristics.
def is_connected(self):
return (
self._conn_handle is not None
and self._tx_handle is not None
and self._rx_handle is not None
)
# Find a device advertising the environmental sensor service.
def scan(self, callback=None):
self._addr_type = None
self._addr = None
self._scan_callback = callback
self._ble.gap_scan(2000, 30000, 30000)
# Connect to the specified device
# (otherwise use cached address from a scan).
def connect(self, addr_type=None, addr=None, callback=None):
self._addr_type = addr_type or self._addr_type
self._addr = addr or self._addr
self._conn_callback = callback
if self._addr_type is None or self._addr is None:
return False
self._ble.gap_connect(self._addr_type, self._addr)
return True
# Disconnect from current device.
def disconnect(self):
if not self._conn_handle:
return
self._ble.gap_disconnect(self._conn_handle)
self._reset()
# Send data over the UART
def write(self, v, response=False):
if not self.is_connected():
return
self._ble.gattc_write(self._conn_handle,
self._rx_handle, v,
1 if response else 0)
# Set handler for when data is received over the UART.
def on_notify(self, callback):
self._notify_callback = callback
def demo():
global root_button_pressed
global current_led_val
ble = bluetooth.BLE()
central = BLESimpleCentral(ble)
not_found = False
def send_CMD(cmd):
try:
central.write(cmd, with_response)
except:
print("TX failed")
def on_scan(addr_type, addr, name):
if addr_type is not None:
print("Found peripheral:", addr_type, addr, name)
central.connect()
else:
nonlocal not_found
not_found = True
print("No peripheral found.")
central.scan(callback=on_scan)
# Wait for connection...
while not central.is_connected():
time.sleep_ms(100)
if not_found:
return
print("Connected")
def on_rx(v):
# command received from peripheral,
# update onboard RGB accordingly.
print("RX", v)
#convert memoryview to str
cmd = str(v,'utf8')
print(cmd)
if v == CMD_LEDON:
np[0] = (3, 3, 0)
np.write()
elif v == CMD_LEDOFF:
np[0] = (0, 0, 0)
np.write()
central.on_notify(on_rx)
with_response = False
while central.is_connected():
if root_button_pressed:
# BOOT button pressed,
# send command to peripheral to toggle LED
root_button_pressed = False
current_led_val = not current_led_val
print("- root_button_pressed -", current_led_val)
if current_led_val:
send_CMD(CMD_LEDON)
else:
send_CMD(CMD_LEDOFF)
time.sleep_ms(400 if with_response else 30)
print("Disconnected")
if __name__ == "__main__":
demo()
