How to read data stream on a specific hardware pin?

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ninene
Posts: 6
Joined: 2019-12-23 04:16

How to read data stream on a specific hardware pin?

#1 Post by ninene »

Hi,

I am junior, especially in Linux, but I got great replies in my first post, so I am asking another question.

How to read the data that's coming/going over any given pin (of the USB/Serial/HDMI/DVI port) of a hardware device? Say, I want to record the bits going over TX pin (only) of a USB port, how can we do that?

Search engines returned tangential answers, touching but not treating the topic (such as this, this & this).
Searching "pin data" turned up this post on our forum, but I don't think that's relevant.

I recently learned everything is a file & the whole /dev/cdrom0 concept really excites me, but I am curious at the same time: can we go one level deeper in abstraction and inspect data coming/going through individual pins? Its obvious the data is there (the WireShark can monitor USB traffic like it was recording Wi-Fi packets :o its genius), but does the latest Linux-kernel allow one to separately read individual pin data?

Cheers :D

chadrick
Posts: 83
Joined: 2016-01-06 00:32

Re: How to read data stream on a specific hardware pin?

#2 Post by chadrick »

That sounds like something that might be done with a Raspberry Pi since you can connect i/o pins. You might be able to have a pin directed to the Pi, read on the Pi, and then output from the Pi on a different pin connected to the final destination. I am not sure if that will mess up timings though.

chadrick

ninene
Posts: 6
Joined: 2019-12-23 04:16

Re: How to read data stream on a specific hardware pin?

#3 Post by ninene »

chadrick wrote:That sounds like something that might be done with a Raspberry Pi since you can connect i/o pins. You might be able to have a pin directed to the Pi, read on the Pi, and then output from the Pi on a different pin connected to the final destination. I am not sure if that will mess up timings though.
Exactly.

I had a similar thought & am trying to understand RPi.GPIO (python package)'s source code because it's the official RPi way to read/write at GPIOs. The source code has too many files, IDK where to look.

Thanks.

ninene
Posts: 6
Joined: 2019-12-23 04:16

Re: How to read data stream on a specific hardware pin?

#4 Post by ninene »

Can fellow developers who write/port hardware drivers, please shed some light on this topic? Is this even possible?

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