How to TX/RX on same serial port

Embedded Devices Plug N' Play
1

I have noticed that the discussion on how to do RX/TX on the serial port on Connect ME, and similar platforms, comes back again. I am posting a small example that outlines the skeleton on how I did it. I had to remove and change things that relate to our product, so I don’t get in trouble, but one can easily get the idea. This also means that the code will most likely not work as-is; I just don’t have time to pats around with it, so you will have to do some work. Feel free to use it and abuse it - just do that at your own risk.
I used mutex locking to achieve transfer.
You can also look around for instructions on how to maximize the speed of the serial ports if you need – they should be still floating in the posts, so I won’t repeat them here.
I am not claming that this is the way to do it. It is only an example on how I did it using Digi examples and voodoo and got good results.
Just call the serial_threads_start is from your applicationStart.

Enjoy.

2

This code example would be interesting, unfortunately it seems to be gone. Maybe somebody can re-post it?

3

hgiritzer,

Since the original post is from 2004, I assume that ieftimovski was using an original ME with NetOS 4 or 5. The way NetOS uses the serial port has completely changed and any code from then wouldn’t work.

-Erik

4

The post is from Jul 2, 2007, but anyway rather old, that’s true.

Nevertheless a small example of how to use the serial port from within a C program (Embedded Linux) and the steps to free the serial port for this application (disable console and what there might be necessary) would be really helpful.

5

Sorry, you are right, I was looking at the wrong date.

It does appear that he is using NetOS though, unless you have an applicationStart in µLinux.

I have used serial ports extensively (written drivers even) with full Linux. The way UNIX works, I would assume that it is identical. What do you want to know?

-Erik

6

Well, I got it to work in the meantime.

My problem was causes by a misconfigration of the DigiME Embedded Linux (“make xconfig”):

Additionally to the needed “Digi NS921x serial port support” there was the “8250/16550 and compatible serial support” selected, which rendered the serial port unusable (not communicating).

After removal of the “8250/16550 and compatible serial support” it worked as expected.

Thanks,
Helmut