topic Re: I don't know 0~5KHz Freq for PWM function. in S12 / MagniV Microcontrollers

I don't know 0~5KHz Freq for PWM function.

Kr_Blue — Tue, 07 Dec 2010 16:12:01 GMT

.hi. Everyone.

I want know 0,1,2,3,4, ~ 4998,4999,5000 Hz Freq for PWM function.

PWM Setting -> Channel clock period = 10KHz

input data = 0~1023

16bit PWM

ex) if i want 1hz, 10KHz / 1Hz = 10K = PWMPER01

10KHz / 2Hz = 5K = PWMPER01

10KHz / 700Hz = 3 = PWMPER01

10KHz / 701Hz = 3 = PWMPER01

10KHz / 702Hz = 3 = PWMPER01

10KHz / 703Hz = 3 = PWMPER01

and I want 700,701,702,703Hz etc..... but only PWMPER01 = 3 !!!!

so Output PWM is only 700Hz.

I want solution.

input data is 1,2,3,4,5,6,7,8,etc.....

Output Hz is 1,2,3,4,5,6,7,8 etc Hz

Re: I don't know 0~5KHz Freq for PWM function.

kef — Tue, 07 Dec 2010 17:18:48 GMT

You need at least 25MHz PWM clock to be able to tune PWM frequency up to 5kHz with 1Hz resolution. 10kHz is certainly not enough.

Minimum PWM frequency in 16bits mode at 25MHz clock is 382Hz, so you you need to prescale 25MHz /2 for frequencies 191-381Hz, -"- 25MHz /4 for 95-190Hz, etc.

Re: I don't know 0~5KHz Freq for PWM function.

Kr_Blue — Wed, 08 Dec 2010 12:45:05 GMT

Thank you for you'r answer.

Your answer was the setting.

PWMPRCLK = 0x22; // BUS Clk / 4 = 3000000

// BUS Clk = 12MHz

PWMSCLA=0x01; // PWMPRCLK / (2*PWMSCLA) = 3000000 / (2 *1) = 1500000

PWMSCLB=0x01;

And good operation.