Low Frequency PWM with PIC12F1840

[ashimotok0]

Hi, I need to generate a Low Frequency PWM , preferrably with an 8 pin PIC device ... the PIC isn't doing much else other than generating a 3-stage PWM output ( i.e PWM 1 value for a period, the PWH 2 for a time period and then Period 3 continuous, until an input is triggered or the PIC is reset. The base frequency needs to around 250 Hz though. Am I correct in thinking this should be achievable with the PWM module on a PIC12F1840 with the internal oscillator set to 32kHz ? It's for a hydraulic valve application.

[Anobium]

By my calcs ( using the compiler ) the max chip frequency would be 4mHz for that slow PWM signal.

You may be to do this will a timer and just generate your own signal at 32 mHz.

Evan

#chip PIC12F1840, 4 
#option Explicit

    #define PWM_Freq 0.25  'Set frequency in KHz
    #define PWM_Duty 50    'Set duty cycle to 80 %
    PWMOn                  'Turn on the PWM

    WAIT 10 s              'Wait 10 seconds
    PWMOff                 'Turn off the PWM

[ashimotok0]

Thanks Evan ... really appreciate your help ... I need to get a prototype board set up for the PIC12F1840, so it may be a couple of days before I can test.

I line 2 should it be: #define PWM_Duty 50 'Set duty cycle to 50 %

Also "You may be to do this will a timer and just generate your own signal at 32 mHz." should this be MHz ?

[Anobium]

I line 2 should it be: #define PWM_Duty 50 'Set duty cycle to 50 %

You are correct.

Also "You may be to do this will a timer and just generate your own signal at 32 mHz." should this be MHz ?

You would have to set the timer2 to interrupt at the frequency you need. Then toggle the output port.

[c-conversion]

You might be able to try this perhaps?

A "simple" way of generating low frequency PWM, and it looks as though it was written for a 12F1840 too.

https://sourceforge.net/p/gcbasic/discussion/projects&guides/thread/807f5e795b/#a92e