How to write decimal value 1 from bluepy to ble device

Question

I have this code I want to write the decimal value 1 to a ble device from a python script using bluepy:

#!/usr/bin/env python

import bluepy.btle as btle
print ("outside")

def letsgobaby():
  print ("turning1on")
  p = btle.Peripheral("bb:00:00:15:27:19") #zl-rc04a

  # GET SERVICES
  services=p.getServices()
  for service in services:
     print service

  # NORMAL get to write to ...
  s = p.getServiceByUUID("0000ffe0-0000-1000-8000-00805f9b34fb") #ffe0
  c = s.getCharacteristics()[0]

  #1 is relay1on, 2 is relay1off
  c.write(1)
  p.disconnect()

if __name__ == "__main__":
  letsgobaby()

but I get this error:

pi@raspberrypi:~/Documents/python/failedPythonBLE $ python 1on.py
outside
turning1on
Hallo from Peripheral
discovering services
Hello
Service <uuid=Generic Attribute handleStart=8 handleEnd=11>
Service <uuid=Generic Access handleStart=1 handleEnd=7>
commonName= 0000ffe0-0000-1000-8000-00805f9b34fb
commonName= ffe0
Service <uuid=ffe0 handleStart=12 handleEnd=17>
17
Traceback (most recent call last):
File "1on.py", line 43, in <module>
letsgobaby()
File "1on.py", line 39, in letsgobaby
c.write(1)
File "/usr/local/lib/python2.7/dist-packages/bluepy/btle.py", line 168, in write
return self.peripheral.writeCharacteristic(self.valHandle, val, withResponse)
File "/usr/local/lib/python2.7/dist-packages/bluepy/btle.py", line 519, in writeCharacteristic
self._writeCmd("%s %X %s\n" % (cmd, handle, binascii.b2a_hex(val).decode('utf-8')))
TypeError: must be string or buffer, not int

You need the data to be serialized to send. Maybe [`int.to_bytes`](https://docs.python.org/3/library/stdtypes.html?highlight=to_bytes#int.to_bytes) works? — sshashank124, Jan 05 '20 at 05:19
That method is available from python 3.2 onwards: https://stackoverflow.com/questions/21017698/converting-int-to-bytes-in-python-3 — sshashank124, Jan 05 '20 at 05:33
You can try any of the other approaches mentioned in the question linked above — sshashank124, Jan 05 '20 at 05:35
ok would that work though? That would convert int to bytes and I need decimal, dont I? — marciokoko, Jan 05 '20 at 20:21
You convert it back on the receiving end. You cannot send arbitrary data. You need to serialize it into bytes or a string and do the reverse on the other end — sshashank124, Jan 06 '20 at 04:00
I don't have access to the ble device's program in a way that would let me modify what it receives. I have to send what it is designed to receive, same as the original android app does. — marciokoko, Jan 06 '20 at 18:18
Well, then I believe you probably want to send it a single byte which is a `0` or a `1`. This can be done by `b'\x00'` or `b'\x01'` — sshashank124, Jan 06 '20 at 18:20
I already tried ```c.write(b'\x00')``` but it doesnt work. The relay doesnt click as it does with the app — marciokoko, Jan 06 '20 at 21:02

How to write decimal value 1 from bluepy to ble device

0 Answers0