Send/receive data from/to Raspberry Pi to/from Arduino with HM-10 (Bluetooth LE module)

Question

My goal is to send a string from an Arduino via an HM-10 bluetooth module to a Rasperry Pi. I do this today by connecting the HM-10 on the Arduino to another HM-10 module (master/slave) and then from that module to the Raspberry Pi via USB Serial adapter which gives me a /dev/ttyUSB0 that I can read. I would like to just have the Arduino's HM-10 connect up directly to the Bluetooth of the Raspberry Pi without any extra modules at all.

I found the app "Arduino Bluetooth Controller" (Android) that can connect to the module and serial communication is working.

I also have the HC-05 module and there I can solve it by using rfcomm bind 2 , but that doesn't work on the HM-10.

I'm open to any solution that can do this. Either bind the serial communication using rfcomm (or alternative) like on the HC-05, or try to build an app that is doing the same thing the Android app does, only on the Raspberry Pi.

Answer 1

HM-10 is a BLE device. You'll need to understand BLE programming, which is quite different than classic Bluetooth. There is no standard BLE service for serial communication. The best way on a Pi to use BLE is with the

• noble and bleno modules for node.js.
• Or start by playing with gatttool.

If you are fit in Phyton: The HM-10 style device will send notifications that the Pi's BLE device can read. Basically you need to attach a 'delegate' call-back function to the Peripheral object, and then wait for notifications. The call-back can then process the received data. You'll have to install the bluepy lib on the PI. This sample code writes to an Arduino HC-10 device

import bluepy.btle as btle
p = btle.Peripheral("AA:BB:CC:DD:EE:FF")
s = p.getServiceByUUID("0000ffe0-0000-1000-8000-00805f9b34fb")
c = s.getCharacteristics()[0]
c.write(bytes("Hello world\n", "utf-8"))
p.disconnect() 

Here is some code for reading from an Arduino HC-10 device

import bluepy.btle as btle
class ReadDelegate(btle.DefaultDelegate):
 def handleNotification(self, cHandle, data):
 print(data.decode("utf-8"))
p = btle.Peripheral("AA:BB:CC:DD:EE:FF")
p.withDelegate(ReadDelegate())
while True:
 while p.waitForNotifications(1):
 pass
p.disconnect()

• miccet: I ended up using bluepy like in your example and with some chunking of the incoming data (seems to be a 20 byte limit) it all works great! Thank you!