Re: nxt.error.DirProtError: Specified mailbox queue is empty

[Marcus Wanner]

On Thu, May 16, 2013 at 08:58:51AM -0700, Gianfranco Cecconi wrote:
> Dear All,
> I have installed nxt-python 2.2.2 according to the instructions on the
> website on a clean and up to date Raspberry Pi. My objective is controlling
> a NXT brick running leJOS' latest firmware (0.9.1beta3). I can use the
> brick without issues using leJOS' tools, so I believe connectivity is good.
>
> When I try running the "message_test.py" example, though, I get the error
> message below:
>
> pi@rpi4 ~ $ python nxt-python-2.2.2/examples/message_test.py
> Traceback (most recent call last):
> File "nxt-python-2.2.2/examples/message_test.py", line 13, in <module>
> local_box, message = b.message_read(box, box, True)
> File "/usr/local/lib/python2.7/dist-packages/nxt/brick.py", line 31, in
> poll
> return parse_func(igram)
> File "/usr/local/lib/python2.7/dist-packages/nxt/direct.py", line 190, in
> _parse_message_read
> tgram.check_status()
> File "/usr/local/lib/python2.7/dist-packages/nxt/telegram.py", line 114,
> in check_status
> nxt.error.check_status(self.parse_u8())
> File "/usr/local/lib/python2.7/dist-packages/nxt/error.py", line 85, in
> check_status
> raise ex
> nxt.error.DirProtError: Specified mailbox queue is empty
>
>
> I googled the error message but could not find anything. Do you have any
> advice? Thank you in advance.

This is usually due to the USB/BT connection desyncing. I most often see
it in association with repeated i2c sensor queries or motor braking
chatter. This might be due to leJOS not behaving as expected, so you
could try using the default firmware. It could also just be that
specific example causing problems, so try one of the others (mary.py
doesn't require anything to be connected) and see if it works. I don't
think this has anything to do with the rpi platform, as I have never had
any issues with it. Sorry you're having problems. Good luck!

--
Marcus Wanner