Error in Python Implementation of ble_cmd_attributes_write

[bsalinas]

When I call:

handle=15
value='01'
ble.send_command(ser, ble.ble_cmd_attributes_write(handle, 0, value))
ble.check_activity(ser, 1)

I get the following error:

Traceback (most recent call last):
  File "test.py", line 14, in <module>
    machine.groups[0].startBrewing()
  File "/Users/ben/Github/bt4prototype/MockEspresso/Group.py", line 86, in startBrewing
    listener.didStartBrewing(self.id)
  File "/Users/ben/Github/bt4prototype/MockEspresso/EspressoMachine.py", line 32, in didStartBrewing
    self.bluetooth.write_attribute(24,'01')
  File "/Users/ben/Github/bt4prototype/MockEspresso/Bluetooth.py", line 55, in write_attribute
    self.ble.send_command(self.ser, self.ble.ble_cmd_attributes_write(handle, 0, value))
  File "/Users/ben/Github/bt4prototype/bglib.py", line 172, in ble_cmd_attributes_write
    return struct.pack('<4BHBB' + str(len(value)) + 's', 0, 4 + len(value), 2, 0, handle, offset, len(value), b''.join(chr(i) for i in value))
  File "/Users/ben/Github/bt4prototype/bglib.py", line 172, in <genexpr>
    return struct.pack('<4BHBB' + str(len(value)) + 's', 0, 4 + len(value), 2, 0, handle, offset, len(value), b''.join(chr(i) for i in value))
TypeError: an integer is required

I think the problem line is Line 172 in bglib.py
It reads:

return struct.pack('<4BHBB' + str(len(value)) + 's', 0, 4 + len(value), 2, 0, handle, offset, len(value), b''.join(chr(i) for i in value))

When I change it to:

return struct.pack('<4BHBB' + str(len(value)) + 's', 0, 4 + len(value), 2, 0, handle, offset, len(value), b''.join(i for i in value))

I am able to successfully write attributes.

Am I overlooking something?

[jrowberg]

Hi @bsalinas,

Your solution works, but I wrote the code under the assumption that the values being written would be byte arrays rather than string literals, and without extra code I don't think there's a simple way to handle both seamlessly. If you change your "value" definition to the following:

value = [ 0x30, 0x31 ]

...then it should work without changes. For efficiency, data sent over BLE is often sent in compact binary form rather than strings, which is why I made that design choice. Does that work?

[bsalinas]

Thanks for the clarification. That will work just fine.
On Aug 29, 2013 3:54 PM, "Jeff Rowberg" notifications@github.com wrote:

Hi @bsalinas https://github.com/bsalinas,

Your solution works, but I wrote the code under the assumption that the
values being written would be byte arrays rather than string literals, and
without extra code I don't think there's a simple way to handle both
seamlessly. If you change your "value" definition to the following:

value = [ 0x30, 0x31 ]

...then it should work without changes. For efficiency, data sent over BLE
is often sent in compact binary form rather than strings, which is why I
made that design choice. Does that work?

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