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Having trouble with the PWM setup

Question asked by hoang thanh on Jul 12, 2006
Latest reply on Jul 17, 2006 by hoang thanh
Using Code warrior special edition
version 5.7.0
Build 1932
Full chip simulation but i intend to use a HC12 (S12DP512)

Im currently trying to configure PWM channels to work with 16 bits

From the .pdf file i found:

"The PWMCTL register contains four control bits, each of which is used to concatenate a pair of PWM channels into one 16-bit channel."

Here is my code


void setupPWM(void){  PWMPOL = 170; /* outputs are high at the beginning of the period, then go low when the duty count is reached. */  PWMCAE = 0;   /* operate in left aligned output mode. */  PWMCLK = 0;   /* Clock B is the clock source for PWM channel 7 and 3, Clock A is the clock source for PWM channel 1and 5. */  PWMPRCLK = 0; /* Clock A = Clock B = Bus Clock */  PWMCTL = 255; /* Channel 0-1 , 2-3 , 4-5 , 6-7 concatenated */  PWMSDN = 0;   /* Disable Emergency shutdown */  PWMPER01 = 8000; /* setup for PERIOD */  PWMDTY01 = 4000; /* setup for DUTY CYCLE */  PWME = 255;   /* Enable PWM function on Port P for all channel */}void main(void){  setupPWM();  EnableInterrupts;  for(;;){  }}


Then im using the true-time simulator
with a LED as the visualisation for the adress 0x258 of the PTP byte
and i have no reaction

The documentation mentionned to set PWMPERx > PWMDTYx
which i did

then i tried this ( these examples are for a duty cycle around 50%)


PWMPER01 = 8000;PWMDTY01 = 3841;

 and with this the LED is working properly

I think the simulator does a comparison between each 8 bits PWMPER1 and PWMDTY1 or PWMPER0 and PWMDTY0 to check the condition "PWMPERx > PWMDTYx"

well can someone help me