Kinetis Microcontrollers中的主题 Re: TPM count set to zero

TPM count set to zero

calvinday — Thu, 03 Mar 2016 20:25:24 GMT

I am using a K66 and the documentation says writing any value to the COUNT register sets it to zero.

I have tried that and cannot see it reset in the debugger. Is there something else I have to do to cause a reset?

Re: TPM count set to zero

Alice_Yang — Fri, 04 Mar 2016 06:05:31 GMT

Hello Calvin,

Could you please attach your project, that we can check it and help you sooner.

Alice

Re: TPM count set to zero

calvinday — Sun, 06 Mar 2016 15:35:24 GMT

// turn off low power timer
LPTMR_BWR_CSR_TEN(LPTMR0, (uint8_t)false);

// clear interrupts
TPM_WR_STATUS(TPM2, 1 << TPM_STATUS_TOF_SHIFT);
TPM_WR_STATUS(TPM2, 1 << TPM_STATUS_CH0F_SHIFT);

// turn off tpm clocks
TPM_HAL_SetClockMode(TPM1, kTpmClockSourceNoneClk);
TPM_HAL_SetClockMode(TPM2, kTpmClockSourceNoneClk);

TPM_HAL_ClearCounter(TPM1);
TPM_HAL_ClearCounter(TPM2);

// restart this timer when lptmr overflows
TPM_HAL_SetTriggerMode(TPM1, true);
TPM_HAL_SetTriggerMode(TPM2, true);

TPM_HAL_SetClockMode(TPM1, kTpmClockSourceModuleClk);
TPM_HAL_SetClockMode(TPM2, kTpmClockSourceModuleClk);

// reset counters
lptmrCnt = 0;
ppsTotal1 = 0;
ppsTotal2 = 0;

// reenable lptmr to overflow in 10 msec
LPTMR_BWR_CSR_TEN(LPTMR0, (uint8_t)true);

Re: TPM count set to zero

Alice_Yang — Mon, 07 Mar 2016 04:11:35 GMT

Hello Calvin,

From your code , have you turn on the clock of LPTMRO ?

And do you want operate the LPTMR0, if yes , i have not find about your this words

"writing any value to the COUNT register sets it to zero" of LPTMR0 .

Alice

Re: TPM count set to zero

cutworth — Mon, 07 Mar 2016 09:30:15 GMT

Hi Calvin,

Can you show me a dump of the TPM module registers? Did you see CMOD bits set for TPMx_SC register?

Hao

Re: TPM count set to zero

calvinday — Mon, 07 Mar 2016 12:05:45 GMT

43.4.2 Counter (TPMx_CNT)

The CNT register contains the TPM counter value.

Reset clears the CNT register. Writing any value to COUNT also clears the counter.

When debug is active, the TPM counter does not increment unless configured otherwise.

Reading the CNT register adds two wait states to the register access due to

synchronization delays.

Re: TPM count set to zero

calvinday — Mon, 07 Mar 2016 12:36:37 GMT

Before TPM_HAL_ClearCounter(TPM2);

After.

Re: TPM count set to zero

calvinday — Mon, 07 Mar 2016 13:32:23 GMT

I found this:

43.5.3.3 Counter Reset

Any write to CNT resets the TPM counter and the channel outputs to their initial values

(except for channels in output compare mode).

TPM2 is in the capture mode so that shouldn't be an issue.

Re: TPM count set to zero

calvinday — Mon, 07 Mar 2016 13:35:52 GMT

I was thinking I could use the software trigger mode and reload to zero on trigger. But I don't see how to cause a software trigger.

Re: TPM count set to zero

calvinday — Mon, 07 Mar 2016 15:03:31 GMT

By disabling the clocks with this statement TPM_HAL_SetClockMode(TPM1, kTpmClockSourceNoneClk), the timers would not reset. Instead, I leave them running.

This is all that is required at this point.

TPM_HAL_ClearCounter(TPM1);

TPM_HAL_ClearCounter(TPM2);

Re: TPM count set to zero

Alice_Yang — Wed, 09 Mar 2016 11:09:34 GMT

Hello Calvin,

There is a reset function you can use :

Have a great day,
Alice Yang

-----------------------------------------------------------------------------------------------------------------------
Note: If this post answers your question, please click the Correct Answer button. Thank you!
-----------------------------------------------------------------------------------------------------------------------