DAC software trigger not working

kerivolans — Tue, 10 Mar 2015 19:52:42 GMT

I am using the KL25Z development board. I'm trying to put data into the next space in the buffer, then am incrementing the buffer pointer to trigger the conversion.

Only DAC0_DAT0H and DAC0_DAT0L have an impact on the output wave. The software trigger is clearly not causing the buffer to increment, and it seems that the buffer is not being enabled.

When hardware trigger is set up instead (and PIT is set up) it works as expected. I would prefer to be able to use software trigger.

#include "MKL25Z4.h"
#include "start.c"
int main(){


  SIM_SCGC5   |= SIM_SCGC5_PORTE_MASK;
  SIM_SCGC6 |= SIM_SCGC6_DAC0_MASK;  
  PORTE_PCR30 &= (uint32_t)~(uint32_t)((PORT_PCR_ISF_MASK | PORT_PCR_MUX(0x07))); 
  MCG_C1 |= (1<<2);        
  MCG_C4 |= (1<<7); 
  MCG_C4 |= (1<<5);                
  SIM_COPC = 0x00; //Disables the watchdog timer.   
  
  //DAC0_C0 = 1<<5;
  //DAC0_C1 = 1;
  //DAC0_C2 = 1;
  //DAC0_C0 = 1<<7;
     
     DAC0_C0 |= DAC_C0_DACTRGSEL_MASK;
   
    /* Normal buffer mode */
    DAC0_C1 &= ~DAC_C1_DACBFMD_MASK;
   
    /* Enables buffer read ptr */
    DAC0_C1 |= DAC_C1_DACBFEN_MASK; 
   
    /* Selects the upper limit of the DAC buffer */
    DAC0_C2 |= DAC_C2_DACBFUP_MASK;
   
    /* Lastly, turn on the DAC */
    DAC0_C0 |= DAC_C0_DACEN_MASK;




 


          int sequence[38] = {1 ,2 ,2 ,2 ,3 ,4 ,5 ,6 ,7 ,9 ,12 ,15 ,18 ,23 ,28 ,36 ,44 ,56 ,69 ,87 ,108 ,136 ,169 ,212 ,265 ,331 ,414 ,517 ,646 ,808 ,1010 ,1262 ,1578 ,1972 ,2465 ,3081 ,3852 ,4815};



while(1){
  for (int x = 0; x < 38; x +=2){
 int temp_low = sequence[x];
 int temp_high = temp_low >>8;
    DAC0_DAT1H =   temp_high;    
    DAC0_DAT1L =   temp_low;
    DAC0_C0 |= 8; //increment buffer pointer
    
     temp_low = sequence[x+1];
  temp_high =  temp_low >>8;
    DAC0_DAT0H =   temp_high;    
    DAC0_DAT0L =  temp_low;
    DAC0_C0 |= 8; /increment buffer pointer
}
  return 0;
  }

Re: DAC software trigger not working

xiangjun_rong — Wed, 11 Mar 2015 03:50:55 GMT

Hi, Volans,

In software triggering mode, after you write the DAC0_DAT0H/DAC0_DAT0L, you should set the DACSWTRG bit to launch the conversion.

Pls use the follo0wing code:

while(1)

{

DAC0_DAT0H = temp_high;

DAC0_DAT0L = temp_low;

DAC0_C0|=0x10; //setting the DACSWTRG bit to launch the DAC conversion immediately

}

Pls have a try.

XiangJun Rong

Re: DAC software trigger not working

kerivolans — Wed, 11 Mar 2015 17:26:18 GMT

That's embarrassing. Thanks a lot!

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