Re: EPICS support for device to monitor Digital I/O

[Jörn Dreyer via Tech-talk <tech-talk at aps.anl.gov>]

Dear Pra,

I took a quick look at the hardware and have some points to remark:

1) you talk about TTL signals which are defined to be 0 - 5V levels. This board can only handle signal up to 3.3V.
Keep that in mind.

2) If you connect this board to a Linux PC and load the correct driver the GPIO part should show up as /dev/gpiochipX.
I am not aware of a generic driver in EPICS that can handle individual GPIO lines. That would probably need to be written.

3) For such a purpose I used a Texas Instruments DAQ card which has EPICS support, but is quite expensive.
Another option would be a Measurement Computing digital IO card supported by the comedi driver in the Linux kernel. But this requires also
some coding in EPICS. I used that to trigger a camera by software when an TTL input signal fired an input on the card.

Hope that helps,

Jörn
Am Freitag, 20. Juni 2025, 08:31:06 Mitteleuropäische Sommerzeit schrieb P B via Tech-talk:
> Hello,
> 
> I am relatively new to EPICS. I am trying to look for an option to monitor
> a single TTL signal on a Linux PC running EPICS.
> 
> Using something like a DAQ is overkill. Ideally, I am thinking of something
> like the FT232H chip
> <https://urldefense.us/v3/__https://www.adafruit.com/product/2264?srsltid=AfmBOopZMcypFKlrUFJei4oyVXH63L2NtuB1rB5JlEEYTbAG-Ag7uO-Y__;!!G_uCfscf7eWS!d4RnFD_jM2oa4yAdin11b0BgqS9IAnXW4ytLQizY2Hb9tFQRwhJLF7tyPlQ6HDjy34L0QnptkYMgIz883SnZbUE$ >.
> Is there support for something equivalent to this? Or any suggestions on a
> quick and easy way to achieve this within EPICS?
> 
> Thanks.
> 
> Pra
>