Reading data from '/run/mpa/qvio' using python

[Nishkala]

How can we read data from the pipe /run/mpa/qvio in python

[modaltb]

Hi @Nishkala ,

I haven't tried this yet, but it's just a file that you are reading from basically (a named pipe), so something like this may get you reading? --> https://stackoverflow.com/questions/39089776/python-read-named-pipe

In order to parse what you are reading, you will need to use the C headers to see what bytes are what, which is shown here: https://gitlab.com/voxl-public/voxl-sdk/core-libs/libmodal-pipe/-/blob/master/library/include/modal_pipe_interfaces.h#L880

[Nishkala]

@modaltb, the links provided were insightful

Before running a python script similar to the one provided in the link, I executed the commands

1. 'cat run/mpa/qvio/info': I was able to see information pertaining to qvio.
2. 'cat run/mpa/qvio/control': I was able to see the message continuously printed related to 'reset_hard_qvio'
3. 'cat run/mpa/qvio/request': It was blank

Which pipe should be read to get data in the form of 'vio_data_t'?

[modaltb]

Hi @Nishkala ,

With the warning that I've not yet tried in python but I'm sure it will work

This is the source code for our voxl-inspect-qvio tool, and from there we can see it's looking for a pipe QVIO_EXTENDED_LOCATION
https://gitlab.com/voxl-public/voxl-sdk/services/voxl-qvio-server/-/blob/master/clients/voxl-inspect-qvio.c#L51

That's defined here:
https://gitlab.com/voxl-public/voxl-sdk/services/voxl-qvio-server/-/blob/master/common/voxl_qvio_server.h#L64

The other place to look for defines is in libmodal-pipe:
https://gitlab.com/voxl-public/voxl-sdk/core-libs/libmodal-pipe/-/blob/master/library/include

This is where the inspect tool consumes data:
https://gitlab.com/voxl-public/voxl-sdk/services/voxl-qvio-server/-/blob/master/clients/voxl-inspect-qvio.c#L259

Here's where we parse and print the info:
https://gitlab.com/voxl-public/voxl-sdk/services/voxl-qvio-server/-/blob/master/clients/voxl-inspect-qvio.c#L184