topic Re: DEVKIT-S12G128 PWM in S12 / MagniV Microcontrollers

DEVKIT-S12G128 PWM

robertwynn — Mon, 29 Jan 2018 15:40:32 GMT

I have a DEVKIT-S12G128, 8Mhz crystal. CodeWarrior 5.9.0. The issue I have is with the PWM. I have setup a 24Mhz bus clock and a 24kHz PWM (16bit) channel (10%duty) . Everything looks ok if you look at a few cycles of the PWM. After about 230ms the output STOPS and restarts in another 230ms.

//---------------------------------

// example devkit-s12g128 with 8MHz crystal
// output on pin PP1 (J2-01)
//
// 24khz pwm signal with a 10% duty cycle.
// After about 230ms the output STOPS. It restarts after about 230ms.
//
// At 1% duty the output stops after 22ms. It restarts after about 440ms

#include <hidef.h>
#include "derivative.h"

void SetPEEmodeBUSCLK(byte _synr, byte _refdv, byte _postdiv);

void main(void)
{
ECLKCTL_NECLK = 0;
DDRP =0x02;

SetPEEmodeBUSCLK(0x02, 0x80, 0x00);   // 24MHz BUSCLK from 8 MHZ oscclk, PEE mode

//------------------------------------------------
PWME = 0x00;        // Disable all PWM channels
PWMPOL =0xFF;       // All channels are high an go low
PWMCLK = 0x00;      // All channels are clocked from A or B clock source
PWMCLKAB = 0x00;    // Clock A is the source clock for all channels
PWMPRCLK = 0x00;    // Clock A & B equal to BUS clock
PWMCAE = 0x00;      // left aligned
PWMCTL = 0x10;      // 0-1 concatenated to form 16-bit PWM

PWMPER01 = 1000;    // PWM channel 01 period
PWME = 0x02;        // Enable the channel
PWMDTY01 = 100;     // set duty cycle for 01

//-------------------------------------------------
for(;;)
{
    _FEED_COP();
}

}

void SetPEEmodeBUSCLK(byte _synr, byte _refdv, byte _postdiv)
{
CPMUSYNR = _synr;
CPMUREFDIV = _refdv;
CPMUPOSTDIV = _postdiv;

CPMUOSC_OSCE = 1; //enable external oscillator OSCE

while(!CPMUFLG_UPOSC)
{// you can check for timeot here with error message report
};
while(!CPMUFLG_LOCK)
{// you can check for timeot here with error message report
};

//--- select clocks --------------------
CPMUCLKS = 0B10000011;                   // bus=fPLL/2; COP is clocked from OSCCLK
if(CPMUCLKS != 0B10000011)               // After writing CPMUCLKS register, it is strongly recommended to read
{                                       // back CPMUCLKS register to make sure that write of PLLSEL,
    asm nop;                             // RTIOSCSEL, COPOSCSEL0 and COPOSCSEL1 was successful.
}
}

Re: DEVKIT-S12G128 PWM

danielmartynek — Wed, 31 Jan 2018 14:09:39 GMT

Hi Robert,

I have just run the code on TWR-S12G128 and everything works. It doesn't stop.

Could you monitor BUS clock on ECLK?

Regards,

Daniel

Re: DEVKIT-S12G128 PWM

robertwynn — Wed, 31 Jan 2018 17:42:37 GMT

Daniel

I have monitored ECLK it looks fine. The board does not restart. Here are a few scope plots.

Robert

Re: DEVKIT-S12G128 PWM

danielmartynek — Thu, 01 Feb 2018 15:10:36 GMT

Hi Robert,

Thank you for the plots.

Have you tried running only the code you posted?

The PWM1 function of PP1 has highest priority, so the PWM module controls the pin if enabled.

Unless it is embedded in a project where you could accidently disable the PWM.

Could you halt the program when the PWM is stopped and check all PWM registers?

Regards,

Daniel

Re: DEVKIT-S12G128 PWM

robertwynn — Fri, 02 Feb 2018 01:13:01 GMT

Daniel

That is all the code. I have reloaded all the pwm registers in the main loop and that did not work either. I don't know how to halt the code when the PWM is stopped.

One note the code runs if I don't use the PLL. I need the fast/more accurate clock for my project.

I have mask 0N51A

Robert