CODEWITHSUNDEEP
pythonbluetooth-lowenergybluegiga
Anthony
Anthony

Reputation: 680

Unable to write to BLE112 Characteristic with Pygatt and BLE112

I have been trying for a while to write to a custom gatt characteristic using pygatt and a Bluegiga BLE112D.The device I'm trying to write to is also a BLE112 (not the dongle). I've been using the following python script:

import pygatt

adapter = pygatt.BGAPIBackend()

adapter = pygatt.BGAPIBackend()
adapter.start()
adapter.scan(timeout=1)

device = adapter.connect('88:6b:0f:7e:4e:66',address_type=pygatt.BLEAddressType.public)
characteristic = "8fbfa190-1af2-427c-a22b-3da61b6b7162"
device.char_write(characteristic, bytearray([0x00, 0xFF]))

#check the characteristic
value = device.char_read(characteristic)

print(value)
adapter.stop()

The characteristic I am trying to write to is configured as follows:

<service uuid="8fbfa190-1af2-427c-a22b-3da71b6b7166" advertise="true">
  <description>Table</description>
  <include id="manufacturer" />
  <characteristic uuid="8fbfa190-1af2-427c-a22b-3da61b6b7162" id="xgatt_table">
      <properties read="true" write="true" />
      <value length="2" />
  </characteristic>
</service>

-The script successfully connects with the adapter and the device. -I can read the characteristic just fine and no errors are produced when I write to it, but when I read the characteristic again, the value has not changed. -I've enabled logging and looked through the output, but everything there shows successful processes. -I am able to write to the characteristic using a third party BLE app as well as the blegui app

I'm pretty sure the problem resides with the pygatt script, but am at a loss as to what could be the issue.

To summarize what I'm using: Pygatt with python 3 to connect to a BLE112A through a BLE112D on windows 10.

Upvotes: 2

Views: 1636

Answers (1)

Anthony
Anthony

Reputation: 680

This issue was solved by adding wait_for_response=True as a parameter in the char_write function. So the new write function call is:

device.char_write(characteristic, bytearray([0x00, 0xFF]), wait_for_response=True)

I'm not entirely sure why this is the case, but I believe that the script was reading from the characteristic before the new value was written.

Upvotes: 1

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