AM335x pwm does not take fractional values

nitesh chowdhary

Hi,

I want to use AM335x pwm signal to generate pulse of frequency 10.1 Hz and 0.1% dutycycle. But i have seen that pwm driver does not take fractional values.

So is there any solution for this..?

regards

Nitesh

over 11 years ago

0 Miroslav Kiradzhiyski XID over 11 years ago

TI__Mastermind 25235 points

What software are you using?

Best regards,
Miroslav

0 nitesh chowdhary over 11 years ago in reply to Miroslav Kiradzhiyski XID

Intellectual 460 points

Hi,

I am running linux 3.2 OS, and i am accessing the pwm frequency and duty cycle through sysfs.

regards

Nitesh

0 Miroslav Kiradzhiyski XID over 11 years ago in reply to Miroslav Kiradzhiyski XID

TI__Mastermind 25235 points

Have you seen this page: http://processors.wiki.ti.com/index.php/Linux_Core_PWM_User's_Guide

I think you can enter 99009901 nano seconds for the period value and 99010 nano seconds for the duty cycle.

Best regards,
Miroslav

0 Miroslav Kiradzhiyski XID over 11 years ago in reply to Miroslav Kiradzhiyski XID

TI__Mastermind 25235 points

Actually this is valid for the new kernel 3.12 that comes with SDK v7. I'm sorry for the mistake. It doesn't seem like you can do this with the old driver.

Best regards,
Miroslav

0 nitesh chowdhary over 11 years ago in reply to Miroslav Kiradzhiyski XID

Intellectual 460 points

Well i tried these values, 99009901 nano seconds for the period and 99010 nano seconds for the duty cycle.

But only frequency i am able to get correctly (around 10.09 Hz), not the duty cycle.

do we have any patch to apply the changes which are there in 3.12.. to linux-3.2 kernel?

regards

Nitesh

0 Miroslav Kiradzhiyski XID over 11 years ago in reply to nitesh chowdhary

TI__Mastermind 25235 points

Use the kernel git repository from SDK v7 to see which patches altered the PWM driver since version 3.2 and try to port them back.

Best regards,
Miroslav

0 nitesh chowdhary over 11 years ago in reply to Miroslav Kiradzhiyski XID

Intellectual 460 points

Hi,

I am unable to find the git repo of the SDK v7. can i get the link of the git repo.

regards

Nitesh

0 Miroslav Kiradzhiyski XID over 11 years ago in reply to nitesh chowdhary

TI__Mastermind 25235 points

It's inside the linux kernel folder once you download and install the SDK.

Best regards,
Miroslav

0 nitesh chowdhary over 11 years ago in reply to Miroslav Kiradzhiyski XID

Intellectual 460 points

thanks Miroslav, for the info

regards

Nitesh

Processors

Processors forum

AM335x pwm does not take fractional values