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LPTMR0 as Pulse Counter

Question asked by sebasira on Jun 7, 2013
Latest reply on Jun 7, 2013 by sebasira

Hello everybody!

 

I'm working with K60N512, I'm trying to develop an odometer. I guess the best way to accomplish that is with the pulse counter, to measure wheel pulses, and then get the speed and distance with a simple conversion.

 

But I can not make the counter to increment.

 

This is how I configure the LPTMR0:

 

SIM_SCGC5 |= SIM_SCGC5_LPTIMER_MASK;// Enable LPT Module


// Reset LPTMR module

LPTMR0_CSR = 0x00;

LPTMR0_PSR = 0x00;

LPTMR0_CMR = 0x00;

 

// I choose PRESCALER = 1, because it says 0 is not supported on pusle counter mode

LPTMR0_PSR = LPTMR_PSR_PRESCALE(1) | LPTMR_PSR_PBYP_MASK;  // bypass glicth filter

 

 

LPTMR0_CSR |= LPTMR_CSR_TPS(2);            // Input pin select

LPTMR0_CSR &= ~LPTMR_CSR_TPP_MASK;  // Rising Edge

LPTMR0_CSR |= LPTMR_CSR_TMS_MASK;     // Timer as Pulse Counter

LPTMR0_CSR |= LPTMR_CSR_TEN_MASK;     // Turn on LPTMR

 

Then I've got a function generator (square wave) connected to PTC5 (LPTMR0_ALT2), but the counter valur remains zero.

 

Am I missing something?

 

Thanks in advance!!

 

 

Best Regards,

SebaS

 

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