Warum antwortet das BLE-Programm ble_simple_central.py mit statt mit Daten? ⇐ Python

[Anonymous]

Ich habe die Micropython-Codebeispiele bei Github ausgeführt und die Bluetooth-Beispielprogramme „ble_simple_peripheral.py“ über eine Bluetooth-Verbindung mit „ble_simple_central.py“ verbunden. Das Ausführen der beiden Programme funktioniert einwandfrei, aber wenn „ble_simple_peripheral.py“ Daten empfängt, kann es diese korrekt drucken, während „ble_simple_central.py“ auf auf den Empfang einer Benachrichtigung vom Peripheriegerät reagiert. Als Hardware wurden zwei „Raspberry Pi Pico W“-Boards verwendet.
Hat jemand eine Idee, warum die „Notify Read“-Operation keine korrekten Daten liefert?
(Ich führe den Code in zwei Thonny-Fenstern aus. Die Demoprogramme erfordern, dass „ble_advertising.py“ auf beide Boards heruntergeladen wird.)
Der Code für „ble_simple_peritheral.py“ und „ble_simple_central.py“ von Github ist unten aufgeführt. Die entscheidenden Codeteile finden Sie in der Klassendefinition und am Ende des Listings in ble_simple_central.py-„demo“, wo die „on_notify“-Behandlung eingerichtet ist:

Code: Select all

# "ble_simple_peripheral.py".  This program output received data correctly!
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_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 demo():
ble = bluetooth.BLE()
p = BLESimplePeripheral(ble)

def on_rx(v):
print("RX", v)

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()

Code: Select all

#Short cutout from ble_simple_central.py:
# Set handler for when data is received over the UART.
def on_notify(self, callback):
self._notify_callback = callback
....

def on_rx(v):
print("RX", v)

central.on_notify(on_rx)

Code: Select all

# "ble_simple_central.py".  This program prints received data as: "RX: 
import bluetooth
import random
import struct
import time
import micropython

from ble_advertising import decode_services, decode_name

from micropython import const

_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 self._conn_handle is None:
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():
ble = bluetooth.BLE()
central = BLESimpleCentral(ble)

not_found = False

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):
print("RX", v)

central.on_notify(on_rx)

with_response = False

i = 0
while central.is_connected():
try:
v = str(i) + "_"
print("TX", v)
central.write(v, with_response)
except:
print("TX failed")
i += 1
time.sleep_ms(400 if with_response else 30)

print("Disconnected")

if __name__ == "__main__":
demo()