Reading logic states on EVM ports

[Linux-SWAT]

Hi,

I would like to read e.g. 0 and 5V on some EVM ports. I have no idea about how to do that.

On the EVM documentation, I see :
-page 24-26, pins of the J20 connector seem to have to be connected to things like screen or timers.
-page 43-47, quite the same
I expected to find things like "port n, GPIO m, do what you want with it".

On the software side, I guess I have to read things in /proc or /sys ?

 

[Letalis Sonus]

I expected to find things like "port n, GPIO m, do what you want with it".

Generally speaking, GPIO pins on such complex chips are rarely just available. They are usually being multiplexed with various other functions and will have to be set up in GPIO mode first, which is something every manufacturer and even chip family does differently... I have no idea how the kernel handles this, it might require a very HW specific kernel module to expose them.

 

[Linux-SWAT]

Ah so that would explain lines like on p.48 :
Pin:4 OMAP_Ball:AD6 Mux_mod:6 Signal_name:h_GPIO8_229 Descr:GPIO
And there's a very few like that.
[doublepost=1511046368,1511024597][/doublepost]Found some Pandora-related useful information there :
https://pandorawiki.org/EXT_Connector

 

[rygD]

You should share more details of what you work on with us.

 

[Pocak]

I would like to read e.g. 0 and 5V on some EVM ports.

Careful there, IO cells are 1.8V or 1.2V. 5 volts will damage the chip. Get the "Data Manual" (swps051) to see which ball is capable of what. I just looked, the DISPC pins are 1.8V only.

On the software side, I guess I have to read things in /proc or /sys ?

See https://elinux.org/GPIO

 

[Linux-SWAT]

Well I would like to do micro-controllers exercises backed with a more powerful CPU.

Yes I must be careful with Volts ;^) .
Thanks for the link.

I also have to buy a connector for the EVM as the pins aren't naked.