TPM FRDMK25

ciful — Tue, 16 Dec 2014 10:38:13 GMT

Good morning to everyone.

I'm new to kinetis microcontroller and I don't understand about TPM module.

I have just programmed my frdm k25 to use the TPM module. In particular I'd like to obtain

a very simple square wawe on the TPM0 ch0 (1 khz).

Till here I didn't find any problems.

This my code:

// Calls to init module

// FTM0 - channel 0 -> 1 Khz square wave

TPM_TmInit(TPM_TIM0, MCGFLL_PLL, TPM_PRSC_001, 12000);

PORTD_PCR0 = PORT_PCR_MUX(4);

TPM_ChInit(TPM_TIM0, TPM_CH0, OC_TOG_ON_MATCH, 0, CHIE_DISABLE);

// FTM0 - channel 2 -> pwm

PORTD_PCR2 = PORT_PCR_MUX(4);

TPM_ChInit(TPM_TIM0, TPM_CH2, PWM_CENTER_HI, 2400, INT_TPM0);

On the second channel I'd like to have a pwm signal. And it works but I want a 20ms period.

If I want this ( I tried) I have to change the module and the prescale values if I want to obtain this.

But I don't have more the square wave.

So, how it's possible to have a square wawe of 1Kz and a pwm signal with 20 ms period on the same TPM moule ?

The module value affects all channel ?

Could be I have (just for example) for output compare, using the same TPM and different channel naturally but different frequency.

I dont'understand something ? What's wrong in my code ?

Thanks in advance.

// SUPPORT INIT FUNCIONS

// init TMP module

void TPM_TmInit(uint8 tpmtimer, uint8 tpmsrc, uint8 tpmprescaler, uint16 module)

{

TPM_Type *tpm[] = { TPM0, TPM1, TPM2 };

uint32 mask[] = { SIM_SCGC6_TPM0_MASK, SIM_SCGC6_TPM1_MASK, SIM_SCGC6_TPM2_MASK };

if(tpmtimer > 2)

return;

SIM->SCGC6 |= mask[tpmtimer]; // TPM clock gating

SIM->SOPT2 |= SIM_SOPT2_TPMSRC(tpmsrc); // TPM clock source

tpm[tpmtimer]->SC |= TPM_SC_CMOD(0x01) | TPM_SC_PS(tpmprescaler); // TPM always up counting, prescaler clock

tpm[tpmtimer]->MOD = module;

}

// init TMP channel

void TPM_ChInit(uint8 tpmtimer, uint8 channel, uint8 chmode, uint16 cnvalue, uint8 chie)

{

TPM_Type *tpm[] = { TPM0, TPM1, TPM2 };

if((tpmtimer > 2) || (channel > 5))

return;

tpm[tpmtimer]->CONTROLS[channel].CnV = cnvalue;

tpm[tpmtimer]->CONTROLS[channel].CnSC = chmode;

if(chie != 0)

{

tpm[tpmtimer]->CONTROLS[channel].CnSC |= TPM_CnSC_CHIE_MASK;

ConnectInterruptToCortex(chie);

}

Re: TPM FRDMK25

mjbcswitzerland — Tue, 16 Dec 2014 18:02:27 GMT

Hi Claudio

The TMPs have one period that is valid for all of its channels.

You can therefore have one 1kHz clock on one channel (50% PWM) and 3 other different PWM values (eg. 5%, 25% and 78%) on other channels (still at 1kHz base rate).

If you need different PWM outputs with different base frequences you need to use chanels on different TMPs for them so that each can have a different base period.

It is not possible to have different base periods on different channels of a single TPM.

Regards

Mark

Re: TPM FRDMK25

ciful — Tue, 16 Dec 2014 22:52:35 GMT

Mark thank you for your answer.

I tried a lot of combination in interrupt but you are right I have just understand.

In the past I didn't use this module.

I can manage my pwm by other TPM module.

Regards

Claudio

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