Updating FTM CnV and C(n+1)V registers in k66 microcontroller

[bert_haj-ali]

Hello all,

I want the PWM waveforms from FTM0 and FTM3 to be toggled between two values each in period. I have set up the initializations of the timers and synchronized them with each other. Also, I have a separate function that does the PWM update by writing new values to the CnV registers of both FTMs. The issue I have is that between 2 specific values, the update does not occur for 1 FTM but occurs for the other. If I toggle between other values, the update works perfectly.

I don't understand the problem since some times the update happen and some times it does not.

I have the code below: [Note: MOD has the value of 599.]

FTM0:

void initFTM0(void) {
  SIM_SCGC6    |= 0x01000000;
  SIM_SCGC5    |= 0x3E00;
  FTM0_SC      = 0x00;         
  FTM0_CONF    = 0xC0;   
  FTM0_FMS      = 0x00;           
  FTM0_MODE    |= 0x05;    
  FTM0_C0SC    = 0x28;           
  FTM0_C1SC    = 0x28;
  FTM0_C2SC    = 0x28;
  FTM0_C3SC    = 0x28;
  FTM0_COMBINE  = 0x0303;         
  FTM0_COMBINE |= 0x1010;       
  FTM0_COMBINE |= 0x2020;       
  FTM0_DEADTIME = 0x3;            
  FTM0_CNT      = 0x00;           
  FTM0_CNTIN    = 0x00;     
  FTM0_MOD      = MOD;         
  FTM0_SYNC    = 0x02;      
  PORTC_PCR1    = 0x400;         
  PORTC_PCR2    = 0x400;         
  PORTC_PCR3    = 0x400;       
  PORTC_PCR4    = 0x400;          
  FTM0_C0V      = (MOD+1)/2;         
  FTM0_C1V      = (MOD+1);   
  FTM0_C2V      = 0;               
  FTM0_C3V      = (MOD+1)/2;     
}

FTM3:

void initFTM3(void) {
  SIM_SCGC3    |= 0x02000000; 
  FTM3_SC      = 0x00;           
  FTM3_CONF    = 0xC0;         
  FTM3_FMS      = 0x00;       
  FTM3_MODE    |= 0x05;          
  FTM3_C0SC    = 0x28;           
  FTM3_C1SC    = 0x28;       
  FTM3_C2SC    = 0x28;
  FTM3_C3SC    = 0x28;
  FTM3_C4SC    = 0x68;
  FTM3_C5SC    = 0x28;
  FTM3_COMBINE  = 0x030303;       
  FTM3_COMBINE |= 0x1010;         
  FTM3_COMBINE |= 0x202020;       
  FTM3_DEADTIME = 0x00;            
  FTM3_CNT      = 0x00;           
  FTM3_CNTIN    = 0x00;   
  FTM3_MOD      = MOD;       
  FTM3_SYNC    = 0x02;              
  PORTD_PCR0    = 0x400;           
  PORTD_PCR1    = 0x400; 
  PORTD_PCR2    = 0x400;       
  PORTD_PCR3    = 0x400;          
  PORTC_PCR8    = 0x300;       
  PORTC_PCR9    = 0x300;          
  FTM3_C0V      = (MOD+1)/2;       
  FTM3_C1V      = (MOD+1)/2;     
  FTM3_C2V      = 0;                 
  FTM3_C3V      = (MOD+1);        
  FTM3_C4V      = (MOD+1)/2 - 8;   
  FTM3_C5V      = (2*(MOD+1))/2 - 8; 
}

FTM syncing:

void syncFTMs(void) {
  FTM0_CONF |= 0x200;
  FTM3_CONF |= 0x200;
  FTM0_SYNCONF |= 0x80;
  FTM3_SYNCONF |= 0x80;
  FTM0_SC = 0x48;
  FTM3_SC = 0x08;
  FTM0_CONF |= 0x400;
}

Registers update:

void phase_modulator(void) {
  //toggle is a global variable with initial value of false
  if (!toggle) {
    Phi = 270;
    toggle = !toggle;
  }
  else if (toggle) {
    Phi = 240;
    toggle = !toggle;
  }
  FTM0_C0V  = (MOD+1)/2 - Phi;
  FTM0_C1V  = (MOD+1)  - Phi;
  FTM0_C2V  = 0;
  FTM0_C3V  = (MOD+1)/2;

  FTM3_C0V  = (MOD+1)/2 - Phi;
  FTM3_C1V  = (MOD+1)/2;
  FTM3_C2V  = 0;
  FTM3_C3V  = (MOD+1)  - Phi;
  FTM3_C4V  = ((MOD+1) - Phi)/2 - 8;       
  FTM3_C5V  = (2*(MOD+1) - Phi)/2 - 8;

  FTM0_PWMLOAD |= 0x20F;
  FTM3_PWMLOAD |= 0x20F;
}

ISR of FTM0:

void ftm0_isr(void) {
  phase_modulator();
  asm("nop");
}

In the function phase_modulator(), if I use any value other than Phi=270, sometimes only FTM0 gets the update, other times only FTM3.
This is a weird issue really and I don't know if anyone can reproduce it because it happens to me occasionally.
Does anyone know why this happens? I followed the PWM synchronization guidelines in the manual.

Thanks in advance.

[kerryzhou]

Hi  Bert Ali ,

  We have an application note about the FTM synchronization: 

https://www.nxp.com/docs/en/application-note/AN4560.pdf 

please follow the application note to check the code and result, whether you lack something or not.

You also can test it like the AN, whether the result is the same or not.

If you still have issues after you checking the AN, please kindly let me know.

Wish it helps you!

Kerry

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