BluePy BLE Guide for AutoPi Edge devices
Introduction#
AutoPi Core relies on BluePy and Bluez packages built into the Linux core on the device.
Prerequisites#
- AutoPi TMU CM4 or AutoPi CAN-FD Pro device
Installation and Setup#
- Enable bluetooth from Advanced settings:
Using the built-in bluetooth extention#
It is possible to use the bluetooth.scan command to remote scanning for bluetooth device using the built in cloud terminal.
Custom software for basic BluePy usage#
A great example of using the AutoPi edge devices full functionality, is teh usage of creating custom services. Using this extendabilty of the devices you utilize the full functionality of the bluepy library on the device.
Scanning for Devices - Custom Code example#
from bluepy.btle import Scanner, DefaultDelegate
class ScanDelegate(DefaultDelegate): def __init__(self): DefaultDelegate.__init__(self)
def handleDiscovery(self, dev, isNewDev, isNewData): if isNewDev: print(f"Discovered device {dev.addr}") elif isNewData: print(f"Received new data from {dev.addr}")
# Initialize scanner objectscanner = Scanner().withDelegate(ScanDelegate())
# Scan for devices (timeout in seconds)devices = scanner.scan(10.0)
# Print discovered devicesfor dev in devices: print(f"Device {dev.addr} ({dev.addrType}), RSSI={dev.rssi} dB") for (adtype, desc, value) in dev.getScanData(): print(f" {desc}: {value}")Connecting to a Device - Custom Code example#
from bluepy.btle import Peripheral, UUIDimport time
try: # Connect to device device = Peripheral("XX:XX:XX:XX:XX:XX") # Replace with your device's address # Get all services services = device.getServices() for service in services: print(f"Service UUID: {service.uuid}") # Get characteristics for this service characteristics = service.getCharacteristics() for char in characteristics: print(f" Characteristic UUID: {char.uuid}") # Check if readable if char.supportsRead(): print(f" Value: {char.read()}") except Exception as e: print(f"Error: {str(e)}")finally: device.disconnect()Reading and Writing Characteristics - Custom Code example#
from bluepy.btle import Peripheral, UUID
class BLEDevice: def __init__(self, address): self.address = address self.device = None def connect(self): self.device = Peripheral(self.address) def read_characteristic(self, service_uuid, char_uuid): service = self.device.getServiceByUUID(UUID(service_uuid)) char = service.getCharacteristics(UUID(char_uuid))[0] return char.read() def write_characteristic(self, service_uuid, char_uuid, data): service = self.device.getServiceByUUID(UUID(service_uuid)) char = service.getCharacteristics(UUID(char_uuid))[0] char.write(data) def disconnect(self): if self.device: self.device.disconnect()
# Example usageif __name__ == "__main__": device = BLEDevice("XX:XX:XX:XX:XX:XX") try: device.connect() # Example UUIDs - replace with your device's UUIDs service_uuid = "1800" char_uuid = "2a00" # Read value value = device.read_characteristic(service_uuid, char_uuid) print(f"Read value: {value}") # Write value device.write_characteristic(service_uuid, char_uuid, bytes([0x01])) finally: device.disconnect()Handling Notifications - Custom Code example#
from bluepy.btle import DefaultDelegate, Peripheralimport time
class NotifyDelegate(DefaultDelegate): def __init__(self): DefaultDelegate.__init__(self)
def handleNotification(self, cHandle, data): print(f"Notification from handle {cHandle}: {data}")
class BLENotifyDevice: def __init__(self, address): self.device = Peripheral(address) self.device.setDelegate(NotifyDelegate()) def enable_notifications(self, service_uuid, char_uuid): service = self.device.getServiceByUUID(UUID(service_uuid)) char = service.getCharacteristics(UUID(char_uuid))[0] # Enable notifications by writing to the CCCD notify_handle = char.getHandle() + 1 self.device.writeCharacteristic(notify_handle, b"\x01\x00") def wait_for_notifications(self, timeout=1.0): self.device.waitForNotifications(timeout) def disconnect(self): self.device.disconnect()
# Example usageif __name__ == "__main__": device = BLENotifyDevice("XX:XX:XX:XX:XX:XX") try: # Enable notifications for a characteristic device.enable_notifications("service_uuid", "char_uuid") # Wait for notifications while True: if device.wait_for_notifications(1.0): continue print("Waiting...") finally: device.disconnect()Error Handling - Custom Code example#
from bluepy.btle import Peripheral, BTLEDisconnectError, BTLEGattError
class BLEDeviceManager: def __init__(self, address): self.address = address self.device = None self.max_retries = 3 def connect_with_retry(self): for attempt in range(self.max_retries): try: self.device = Peripheral(self.address) print("Connected successfully") return True except BTLEDisconnectError: print(f"Connection failed, attempt {attempt + 1} of {self.max_retries}") time.sleep(1) return False def safe_read_characteristic(self, service_uuid, char_uuid): try: service = self.device.getServiceByUUID(UUID(service_uuid)) char = service.getCharacteristics(UUID(char_uuid))[0] return char.read() except BTLEGattError as e: print(f"GATT error: {str(e)}") except BTLEDisconnectError: print("Device disconnected") self.connect_with_retry() return NoneComplete Application - Custom Code example#
from bluepy.btle import Scanner, Peripheral, DefaultDelegate, BTLEDisconnectErrorimport timeimport logging
logging.basicConfig(level=logging.INFO)logger = logging.getLogger(__name__)
class BLEDeviceManager: def __init__(self, target_name): self.target_name = target_name self.device = None self.target_address = None def scan_for_device(self, timeout=10): scanner = Scanner() devices = scanner.scan(timeout) for dev in devices: for (adtype, desc, value) in dev.getScanData(): if desc == "Complete Local Name" and value == self.target_name: self.target_address = dev.addr logger.info(f"Found device: {self.target_address}") return True return False def connect(self): if not self.target_address: raise ValueError("No device address available") try: self.device = Peripheral(self.target_address) logger.info("Connected successfully") return True except BTLEDisconnectError as e: logger.error(f"Connection failed: {str(e)}") return False def discover_services(self): services = self.device.getServices() for service in services: logger.info(f"Service: {service.uuid}") chars = service.getCharacteristics() for char in chars: logger.info(f" Characteristic: {char.uuid}") def disconnect(self): if self.device: self.device.disconnect() logger.info("Disconnected")
if __name__ == "__main__": manager = BLEDeviceManager("MyDevice") # Replace with your device name try: if manager.scan_for_device(): if manager.connect(): manager.discover_services() # Add your device-specific operations here time.sleep(5) # Keep connection alive for 5 seconds finally: manager.disconnect()This example provides a complete application structure that you can adapt for your specific needs.
Further Resources#
- BluePy Documentation