Mark Gottscho / HardwareTimersLib

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Fork of HardwareTimersLib by Mark Gottscho

Timer_TPM.cpp@1:7dde0e4d30da, 2014-03-09 (annotated)

Committer:
mgottscho
Date:
Sun Mar 09 01:09:56 2014 +0000
Revision:
1:7dde0e4d30da
Child:
2:5056ec8c52e8
Refactored code so that there can be different timer/frequency combinations. For example, Timer_48MHz now derives from Timer_TPM, which derives from HardwareTimer.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
mgottscho 1:7dde0e4d30da 1 /* Timer_TPM.cpp
mgottscho 1:7dde0e4d30da 2 * Tested with mbed board: FRDM-KL46Z
mgottscho 1:7dde0e4d30da 3 * Author: Mark Gottscho
mgottscho 1:7dde0e4d30da 4 * mgottscho@ucla.edu
mgottscho 1:7dde0e4d30da 5 */
mgottscho 1:7dde0e4d30da 6
mgottscho 1:7dde0e4d30da 7 #include "mbed.h"
mgottscho 1:7dde0e4d30da 8 #include "HardwareTimer.h"
mgottscho 1:7dde0e4d30da 9 #include "Timer_TPM.h"
mgottscho 1:7dde0e4d30da 10
mgottscho 1:7dde0e4d30da 11 //Init class static variable
mgottscho 1:7dde0e4d30da 12 bool Timer_TPM::__initialized_tpm = false;
mgottscho 1:7dde0e4d30da 13 uint16_t Timer_TPM::__rolloverValue = 0xFFFF;
mgottscho 1:7dde0e4d30da 14 uint32_t Timer_TPM::__count = 0;
mgottscho 1:7dde0e4d30da 15
mgottscho 1:7dde0e4d30da 16
mgottscho 1:7dde0e4d30da 17 Timer_TPM::Timer_TPM() :
mgottscho 1:7dde0e4d30da 18 HardwareTimer(20.8333333333) //20.833... ns per tick, roll over at maximum possible value to reduce interrupt frequency
mgottscho 1:7dde0e4d30da 19 {
mgottscho 1:7dde0e4d30da 20 }
mgottscho 1:7dde0e4d30da 21
mgottscho 1:7dde0e4d30da 22 Timer_TPM::~Timer_TPM() {}
mgottscho 1:7dde0e4d30da 23
mgottscho 1:7dde0e4d30da 24 void Timer_TPM::disableTimer() {
mgottscho 1:7dde0e4d30da 25 if (!__valid)
mgottscho 1:7dde0e4d30da 26 return;
mgottscho 1:7dde0e4d30da 27
mgottscho 1:7dde0e4d30da 28 TPM0->SC = 0; //Reset TPM
mgottscho 1:7dde0e4d30da 29 __enabled = false;
mgottscho 1:7dde0e4d30da 30 }
mgottscho 1:7dde0e4d30da 31
mgottscho 1:7dde0e4d30da 32 uint32_t Timer_TPM::getTick() {
mgottscho 1:7dde0e4d30da 33 if (!__valid)
mgottscho 1:7dde0e4d30da 34 return 0;
mgottscho 1:7dde0e4d30da 35
mgottscho 1:7dde0e4d30da 36 //Get raw time
mgottscho 1:7dde0e4d30da 37 __disable_irq();
mgottscho 1:7dde0e4d30da 38 TPM0->CNT = 0; //Need to write to the TPM CNT register in order to read it (buffering)
mgottscho 1:7dde0e4d30da 39 uint16_t tick = TPM0->CNT;
mgottscho 1:7dde0e4d30da 40 uint32_t count = __count;
mgottscho 1:7dde0e4d30da 41 __enable_irq();
mgottscho 1:7dde0e4d30da 42
mgottscho 1:7dde0e4d30da 43 //Convert to ticks
mgottscho 1:7dde0e4d30da 44 return (uint32_t) count * __rolloverValue + tick;
mgottscho 1:7dde0e4d30da 45 }
mgottscho 1:7dde0e4d30da 46
mgottscho 1:7dde0e4d30da 47 void Timer_TPM::__set_tpm(uint16_t count) {
mgottscho 1:7dde0e4d30da 48 //TPM0->SC &= ~TPM_SC_CMOD_MASK; //Stop clock
mgottscho 1:7dde0e4d30da 49 TPM0->CNT = 0; //Set the count register
mgottscho 1:7dde0e4d30da 50 TPM0->MOD = count; //Set the modulo register
mgottscho 1:7dde0e4d30da 51 TPM0->SC |= TPM_SC_TOIE_MASK; //Enable interrupt
mgottscho 1:7dde0e4d30da 52 TPM0->SC |= TPM_SC_CMOD(1); //Start the timer. Timer will increment on the TPM clock edges, not an external clock
mgottscho 1:7dde0e4d30da 53 }
mgottscho 1:7dde0e4d30da 54
mgottscho 1:7dde0e4d30da 55 void Timer_TPM::__isr_tpm() {
mgottscho 1:7dde0e4d30da 56 TPM0->SC |= TPM_SC_TOF_MASK;
mgottscho 1:7dde0e4d30da 57 __set_tpm(__rolloverValue);
mgottscho 1:7dde0e4d30da 58 __count++;
mgottscho 1:7dde0e4d30da 59 }