i.MX ProcessorsのトピックRe: Read ADC on mx28evk

Read ADC on mx28evk

JeromeBaron — Fri, 03 Oct 2014 18:00:42 GMT

Hi everyone,

I want to do a simple read on the lradc pins on the mx28evk. I have read a lot of threads but I could not find the answer to my question or could wrap my head around what I'm missing there.

- In the kernel menuconfig, I have "Low Resolution ADC support" checked, which set CONFIG_MXS_LRADC=y.

- In the target filesystem, I have some files related to lradc:

/sys/devices/platform/mxs-lradc.0

/sys/devices/system/mxs-lradc

/sys/devices/system/mxs-lradc/mxs-lradc-1

/sys/bus/platform/devices/mxs-lradc.0

/sys/bus/platform/drivers/mxs-lradc

/sys/bus/platform/drivers/mxs-lradc/mxs-lradc.0

- I have one dev related to that: /dev/input/ts0

Now, can I, in the filesystem, read the ADCs?

If not, should I do a simple program that use ioctl of a driver? Which driver file?

Regards,

Jerome

Re: Read ADC on mx28evk

alejandrolozan1 — Tue, 07 Oct 2014 22:05:05 GMT

Hi,

There is no driver of ADC in user space. But you can use as reference the touchscreen driver source code to develop your own ADC driver in user space.

If you want to check the touchscreen funcionality in user space you can type:

cat /dev/input/touchscreen0

It seems that there is customer's example at

LRADC with IMX28

Best Regards,

Alejandro

Re: Read ADC on mx28evk

fabio_estevam — Tue, 07 Oct 2014 23:45:55 GMT

On a 3.17 kernel you can read the ADC by doing:

root@freescale /$ cat /sys/bus/iio/devices/iio:device0/in_voltage0_raw

4095

Re: Read ADC on mx28evk

pt — Wed, 08 Oct 2014 05:33:37 GMT

I have found adc test code on the following thread.

https://community.freescale.com/message/313683#313683

Regards

Re: Read ADC on mx28evk

JeromeBaron — Thu, 09 Oct 2014 18:47:53 GMT

Thanks everyone for your answers. I think I'll go with the register access way like suggested by Pt. I already have a section in my code where I rewrite the PINMUX registers so I'll just do the same for the ADC.