BBB ADC - "Device or resource busy"

Mathew Rumsey

Prodigy 70 points

I'm trying to get continuous ADC working on my BBB (4.1.10-ti-r21)

What I do:

echo 1 > /sys/bus/iio/devices/iio\:device0/scan_elements/in_voltage0_en

echo 100 > /sys/bus/iio/devices/iio\:device0/buffer/length

echo 1 > /sys/bus/iio/devices/iio\:device0/buffer/enable

cat /sys/bus/iio/devices/iio\:device0/in_voltage0_raw

What I get:

cat: in_voltage0_raw: Device or resource busy

These steps were followed from TI's "Linux Core ADC User's Guide"

I'm a bit desperate to get this working for my senior project, any and all help would be greatly appreciated!

over 9 years ago

0 Biser Gatchev-XID over 9 years ago

TI__Guru**** 393215 points

Hi,

The message "Device or resource busy" indicates that the ADC is unaccessible at this moment, which is normal when it's working in continuous mode. You need to stop the capture before reading the buffer. You can also refer to the Sample application given in the wiki you refer.

0 Mathew Rumsey over 9 years ago in reply to Biser Gatchev-XID

Prodigy 70 points

Could you please give a suggestion on how to do this? Because when I take the following steps:

echo 0 > /sys/bus/iio/devices/iio\:device0/buffer/enable (disable capture?)

cat /sys/bus/iio/devices/iio\:device0/in_voltage0_raw (now I can read, but I get only one value)

the device returns to one-shot mode, and I lose all my buffered data.

0 Biser Gatchev-XID over 9 years ago in reply to Mathew Rumsey

TI__Guru**** 393215 points

Follow this link: processors.wiki.ti.com/.../Linux_Core_ADC_User's_Guide

0 Mathew Rumsey over 9 years ago in reply to Biser Gatchev-XID

Prodigy 70 points

This is the resource I've used to get to this point. In addition to the command-line method I've explored above, it also talks about applying a patch to the generic_buffer program. This patch introduces compile errors and thus hasn't helped much.

0 Yordan Kovachev over 9 years ago in reply to Mathew Rumsey

TI__Guru**** 161600 points

Hi,

Can you share your dts file, so I can try and reproduce this on my BBB?
Could you verify that your adc & pinmux settings are correct (there are no conflicts with other modules pinmux settings)?

Best Regards,
Yordan

Processors

Processors forum

BBB ADC - "Device or resource busy"