12F1840 PWM Generation

[BLL]

Hi,
I want to control a model r/c servo from the 1840. I need to be able to select either 830 us or 1500us pulse width.

I have looked at lots of posts on PWM, but am still not seeing the wood for the trees! I am using the internal oscillator at 16MHz.

Can someone please help me out, so I can understand how to achieve this?
Thanks
Brian

[PCM programmer]

See the sample code in this link. It uses the CCS driver file servos.c:
http://www.ccsinfo.com/forum/viewtopic.php?t=34560&start=22

[Ttelmah]

You can't.
You need to perhaps use the CCP, rather than the PWM.

Problem is a servo pulse is normally repeated at 25mSec intervals.
From your master clock, the slowest the PWM can go is 245Hz.
The PWM is designed to provide _fast_ pulses without needing CPU
overhead. Not to provide slow pulses like this.

I posted a routine to handle a servo pulse in percent here:
<http://www.ccsinfo.com/forum/viewtopic.php?t=50914&highlight=servo>

This uses the CCP. You'd need 33 for 830uSec.

[BLL]

Hi Ttelmah

Thanks again for your help - I shall go and study your code.

Brian