REXYGEN Community Forum

contactform

Member

Registered: 2015-10-30

Posts: 45

PWM frequency

I'm playing with the PWM pins on the Raspberry Pi now. How can I lock in a frequency. I need a frequency of 1Hz, with 0-100% duty cycle. Is this possible?

Thanks!

jaroslav_sobota

Administrator

Registered: 2015-10-27

Posts: 535

Re: PWM frequency

Hi,
for such a low frequency you can do without hardware PWM. Use a task with 10ms sampling time (this gives you 100 levels within duty cycle of 1s) and put the PWM function block inside. Set pertm=1 (i.e. 1 second, 1 Hz) and you are done. Is there any specific reason to use the hardware PWM?

Hope this helps,
Jaroslav

Last edited by jaroslav_sobota (2016-10-12 13:28:15)

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Monarco HAT for Raspberry Pi - Lightweight I/O for monitoring, archiving and control.
Raspberry Pi in industrial automation!

mikeyh

Member

From: New Zealand

Registered: 2016-04-28

Posts: 44

Re: PWM frequency

Thats for the reply Jaroslav,

I will play with the pwm block and let you know how it goes.

Are you saying because of the low frequency I could use any of the GPIO pins? In this case I could save the hardware pwm pin for something that really needs it.

Cheers

Mike

jaroslav_sobota

Administrator

Registered: 2015-10-27

Posts: 535

Re: PWM frequency

Hi Mike,
exactly. For such a low frequency you can use any GPIO pin.

Jaroslav

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Monarco HAT for Raspberry Pi - Lightweight I/O for monitoring, archiving and control.
Raspberry Pi in industrial automation!