topic Re: TPM channel on K27 in Kinetis Microcontrollers

TPM channel on K27

attiliorossi321 — Sun, 24 Nov 2019 09:31:46 GMT

Good morning.

I'd like to use the TPM counter and its channel for some timing uses.

Prescale must be set at 128, so with a 24 mhz of bus clock I have 187, 5 Khz for tpm clock.

One channel (..ch2) must be set to get an interrupt break at every 1ms. I write the simple code that I use now.

It works properly for just 250 ms. After that, the TPM0 interrupt it does not work anymore and the output is fixed at one.

I don't understand this behavior. Probably something is missing in my code.

Look at CH2

Thanks in advance.

Attilio

#define       TPM_CHANNEL_0               0                                   // tpm channel 0 mask
#define       TPM_CHANNEL_1               1                                   // tpm channel 1 mask
#define       TPM_CHANNEL_2               2                                   // tpm channel 2 mask
#define       TPM_CHANNEL_3               3                                   // tpm channel 3 mask
#define       TPM_CHANNEL_4               4                                   // tpm channel 4 mask
#define       TPM_CHANNEL_5               5                                   // tpm channel 5 mask

#define       TPM_CH0_FLAG               0x01                               // channel 0 event flag
#define       TPM_CH1_FLAG               0x02                               // channel 1 event flag
#define       TPM_CH2_FLAG               0x04                               // channel 2 event flag
#define       TPM_CH3_FLAG               0x08                               // channel 3 event flag
#define       TPM_CH4_FLAG               0x10                               // channel 4 event flag
#define       TPM_CH5_FLAG               0x20                               // channel 5 event flag

#define TPM_OVERFLOW_COUNTER 0x100 // overflow counter flag

This the init function

void InitTimers(void)
{

SIM->SCGC6 |= SIM_SCGC6_TPM0_MASK; // clock gating
SIM->SOPT2 |= SIM_SOPT2_TPMSRC(0x10); // tpm clock source

TPM0->SC = TPM_SC_PS(0x07) | // prescaler divide 0x07 = 128 times
TPM_SC_CMOD(0x01); // tpm increment every tpm counter clock

TPM0->MOD = 46750; // timer period

   // CHANNEL 2 SETTING
   TPM0->CONTROLS[TPM_CHANNEL_2].CnV = 23375;                     // first int. after ~125ms
   TPM0->CONTROLS[TPM_CHANNEL_2].CnSC = (OUT_COMPARE_TOGGLE + TPM_CnSC_CHIE_MASK);

PORTA->PCR[5] = PORT_PCR_MUX(ALTERNATE_FUNCTION_3); // PTA5 wired to out

ConnectInterruptToCortex(TPM0_IRQn); // set TPM0 interrupt
}

This the interrupt

void TPM0_IRQHandler(void)
{
UINT32 status;
UINT32 l;

status = TPM0->STATUS;

   // OVERFLOW
   if(status & TPM_OVERFLOW_COUNTER)
   {
   }

   // CH0
   if(status & TPM_CH0_FLAG)
   {
   }

   // CH1
   if(status & TPM_CH1_FLAG)
   {
   }

   // CH2
   if(status & TPM_CH2_FLAG)
   {
       l = TPM0->CNT;
       l = l + 376;
       l = l % 65535;

TPM0->CONTROLS[TPM_CHANNEL_2].CnV = (UINT16)l;
}

   // CH3
   if(status & TPM_CH3_FLAG)
   {
   }

   // CH4
   if(status & TPM_CH4_FLAG)
   {
   }

   // CH5
   if(status & TPM_CH5_FLAG)
   {
   }

TPM0->STATUS |= status;

}

Re: TPM channel on K27

Robin_Shen — Mon, 25 Nov 2019 07:46:29 GMT

Hi Attilio,

I can see you configure the TPM0 work as OUT_COMPARE_TOGGLE mode.
Since you just need the ch2 get an interrupt break at every 1ms, why not direct configure TPM0->MOD let the period =1ms. Then the fixed TPM0->CONTROLS[TPM_CHANNEL_2].CnV value will always get 1ms interrupt and toggle waveform.(There is no need to modify ch2.CnV so frequently in IRQ)

Best Regards,

Robin

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Re: TPM channel on K27

attiliorossi321 — Mon, 25 Nov 2019 10:34:55 GMT

Hi Robin.

Thanks for your interest.

You are right. But in reality the main purpose of this timer it's to generate a slow pwm frequency on channel 1.

So, I have to keep the MOD register at the desidered period. Usually it's 8 hz. (about 46875 value at 187,5 Khz).

But I wanted to use the same timer to get a 1 ms tick on another output.

Below, I send the total code that I'm using now, so may be more clear for you.

As I wrote the strange thing is at the beginning it works fine and properly. I can see the output toggle every 1ms (500 hz frequency) but suddendly afeter 250ms - 300 ms the TPM0 interrupt is no longer call.

Thanks

Attilio

void InitTimers(void)
{
float bus_tick, frequency, period, duty;
UINT8 duty_cycle;

/* TIMER 0 channels setting */
GetLampParameters(&frequency, &duty_cycle);

   bus_tick = (1.0 / (BUSCLOCK / Power(2, 0x07)));
   period   = (1.0 / frequency) / bus_tick;
    duty     = (period / 100) * duty_cycle;

SIM->SCGC6 |= SIM_SCGC6_TPM0_MASK; // clock gating
SIM->SOPT2 |= SIM_SOPT2_TPMSRC(0x10); // tpm clock source

   TPM0->SC = 0x00UL;
   TPM0->SC |= TPM_SC_PS(0x07);                                           // prescaler divide 0x07 = 128 times
   TPM0->SC |= TPM_SC_CMOD(0x01);                                           // tpm increment every tpm counter clock

TPM0->MOD = (UINT32)period; // timer period

   // channel 1 setting
   TPM0->CONTROLS[TPM_CHANNEL_1].CnV = (UINT32)duty;                       // timer duty cycle
   TPM0->CONTROLS[TPM_CHANNEL_1].CnSC = PWM_EDGE_ALIGN_HIGH_PULSE;           // pwm - no CHIE
   PORTA->PCR[4] = PORT_PCR_MUX(ALTERNATE_FUNCTION_3);                       // PTA4 wired to manage lamp

   // channel 2
   TPM0->CONTROLS[TPM_CHANNEL_2].CnSC = OUT_COMPARE_TOGGLE +\
                                         TPM_CnSC_CHIE_MASK;               // ch2 - out.comp. - CHIE request

TPM0->CONTROLS[TPM_CHANNEL_2].CnV = 375; // first match after ~2ms
PORTA->PCR[5] = PORT_PCR_MUX(ALTERNATE_FUNCTION_3); // PTA5 wired to lamp

ConnectInterruptToCortex(TPM0_IRQn); // set TPM0 interrupt
}

void TPM0_IRQHandler(void)
{
           UINT32   status;
           UINT16   l;
   static UINT8    break_test;

status = TPM0->STATUS;

   // OVERFLOW
   if(status & TPM_OVERFLOW_COUNTER)
   {
       break_test = 1;
   }

   // CH0
   if(status & TPM_CH0_FLAG)
   {
       break_test = 1;
   }

   // CH1
   if(status & TPM_CH1_FLAG)
   {
       break_test = 1;
   }

   // CH2
   if(status & TPM_CH2_FLAG)
   {
       l = TPM0->CNT;
       l = l + 375;
       TPM0->CONTROLS[TPM_CHANNEL_2].CnV = (UINT32)l;
   }

   // CH3
   if(status & TPM_CH3_FLAG)
   {
       break_test = 1;
   }

   // CH4
   if(status & TPM_CH4_FLAG)
   {
       break_test = 1;
   }

   // CH5
   if(status & TPM_CH5_FLAG)
   {
       break_test = 1;
   }

TPM0->STATUS |= status;
}

Re: TPM channel on K27

Robin_Shen — Tue, 26 Nov 2019 09:04:56 GMT

Hi Attilio,

I find the value that you give CnV will greater than TPM0->MOD = 46750;

Please limit the value of CnV.

Best Regards,

Robin

Re: TPM channel on K27

attiliorossi321 — Tue, 26 Nov 2019 13:44:31 GMT

Robin thank you very much.

The solution was in front of me without seeing it.

Have a nice day.

Attilio

Re: TPM channel on K27

winstinalaw415 — Mon, 27 Apr 2020 09:45:16 GMT

Exactly what I needed! You just saved me several hours. Thanks!