Counts pulses on pin p29. Pulse frequency can be up to 48 MHz.

Example, counting 48MHz-pulses on pin p29 generated by pin p22 with PwmOscillator (https://mbed.org/users/geotec/code/PwmOscillator/). Pins p22 & p29 must be connected. Count is triggered when pin p30 = high (I connected oscillator with 9kHz that triggered periodically).

#include "mbed.h"
#include "PwmOscillator.h"
#include "PulseCounter.h"

Serial usbPC(USBTX, USBRX);   // sends log messages via USB to PC terminal
PwmOscillator pulseGenerator; // generates pulses to be count (48 MHz) on pin p22. Connect this pin to p29 (counter input).
PulseCounter pulseCounter;    // counts the pulses on pin p29 between trigger events (= rising edges) on pin p30.

int main() 
{
    usbPC.printf("---> start <---\n");
    pulseGenerator.initWithFrequency(48000000);
    pulseCounter.init();
    pulseGenerator.start();
        
    pulseCounter.start();   
    wait(1);        // waiting 1 second for trigger events (pin30: rising edge). Count pulses between trigger events.
    pulseCounter.stop();
                        
    pulseGenerator.stop();
        
    // read & print pulseCounter results
    uint32_t pulseCounterResults[20];
    pulseCounter.counterArray(&pulseCounterResults[0],sizeof pulseCounterResults / sizeof (uint32_t));
        
    for(int i = 0; i < (sizeof pulseCounterResults / sizeof (uint32_t)); i++) {
        usbPC.printf("counter of trigger event %i = %u\n",i,pulseCounterResults[i]);
    }
    //
        
    usbPC.printf("   finished.\n");
}
Committer:
geotec
Date:
Sat Dec 15 14:26:47 2012 +0000
Revision:
0:157c2fddaa68
Child:
1:83149916f8a9
Initial commit

Who changed what in which revision?

UserRevisionLine numberNew contents of line
geotec 0:157c2fddaa68 1 #include "mbed.h"
geotec 0:157c2fddaa68 2 #include "PulseCounter.h"
geotec 0:157c2fddaa68 3
geotec 0:157c2fddaa68 4 PulseCounter *PulseCounter::instance;
geotec 0:157c2fddaa68 5
geotec 0:157c2fddaa68 6 extern int CLOCK_FREQUENCY;
geotec 0:157c2fddaa68 7
geotec 0:157c2fddaa68 8 void PulseCounter::init()
geotec 0:157c2fddaa68 9 {
geotec 0:157c2fddaa68 10 instance = this; // pointer to instance
geotec 0:157c2fddaa68 11
geotec 0:157c2fddaa68 12 // Power Control for Peripherals Register
geotec 0:157c2fddaa68 13 LPC_SC->PCONP |= (1<<22); // Bit 22: 1 = Timer2 power on
geotec 0:157c2fddaa68 14
geotec 0:157c2fddaa68 15 // Pin Function Select Register
geotec 0:157c2fddaa68 16 LPC_PINCON->PINSEL0 |= (0x3<<8); // Bits 9/8: 1/1 = pin function CAP2.0 (p30)
geotec 0:157c2fddaa68 17 LPC_PINCON->PINSEL0 |= (0x3<<10); // Bits 11/10: 1/1 = pin function CAP2.1 (p29)
geotec 0:157c2fddaa68 18
geotec 0:157c2fddaa68 19 // Peripheral Clock Selection Register
geotec 0:157c2fddaa68 20 LPC_SC->PCLKSEL1 |= (0x1<<12); // Bits 13/12: 0/1 = CCLK ( 96 MHz )
geotec 0:157c2fddaa68 21 // Prescale Register
geotec 0:157c2fddaa68 22 LPC_TIM2->PR = 0x0; // 0 = no prescaling
geotec 0:157c2fddaa68 23
geotec 0:157c2fddaa68 24 // Count Control Register
geotec 0:157c2fddaa68 25 LPC_TIM2->CTCR = 0x7; // Bits 1/0: 1/1 = timer is incremented on rising & falling edges on clock sample capture pin
geotec 0:157c2fddaa68 26 // Bits 3/2: 0/1 = clock sample capture pin: CAP2.1 (p29), (p29 signal is counter clock)
geotec 0:157c2fddaa68 27
geotec 0:157c2fddaa68 28 // Capture Control Register
geotec 0:157c2fddaa68 29 LPC_TIM2->CCR = 0x5; // Bits 2/1/0: 1/0/1 = capture on rising edge / generate interrupt on event
geotec 0:157c2fddaa68 30 // Bits 5/4/3: 0/0/0 = don't capture - this is the clock sample capture pin
geotec 0:157c2fddaa68 31
geotec 0:157c2fddaa68 32 // Set custom method to be called on Timer2 interrupt
geotec 0:157c2fddaa68 33 NVIC_DisableIRQ(TIMER2_IRQn);
geotec 0:157c2fddaa68 34 NVIC_SetVector(TIMER2_IRQn, (uint32_t)&_triggerInterrupt);
geotec 0:157c2fddaa68 35 NVIC_EnableIRQ(TIMER2_IRQn);
geotec 0:157c2fddaa68 36 //
geotec 0:157c2fddaa68 37
geotec 0:157c2fddaa68 38 LPC_TIM2->TCR = 0x2; // Timer2 count reset
geotec 0:157c2fddaa68 39 LPC_TIM2->TCR = 0x0; // Timer2 disabled
geotec 0:157c2fddaa68 40
geotec 0:157c2fddaa68 41 _hasFinishedCounting = true;
geotec 0:157c2fddaa68 42 }
geotec 0:157c2fddaa68 43
geotec 0:157c2fddaa68 44 void PulseCounter::start()
geotec 0:157c2fddaa68 45 {
geotec 0:157c2fddaa68 46 // reset array pointer to first array element
geotec 0:157c2fddaa68 47 int arrayLength = sizeof(_pulseCountArray)/sizeof(uint32_t);
geotec 0:157c2fddaa68 48 for(int i = 0; i < arrayLength; i++) {
geotec 0:157c2fddaa68 49 _pulseCountArray[i] = 0;
geotec 0:157c2fddaa68 50 }
geotec 0:157c2fddaa68 51 _arrayPointer = &_pulseCountArray[0];
geotec 0:157c2fddaa68 52 _triggerCounter = 0;
geotec 0:157c2fddaa68 53 //
geotec 0:157c2fddaa68 54
geotec 0:157c2fddaa68 55 LPC_TIM2->TCR = 1; // Timer2 start
geotec 0:157c2fddaa68 56 NVIC_EnableIRQ(TIMER2_IRQn); // enable capture interrupt
geotec 0:157c2fddaa68 57
geotec 0:157c2fddaa68 58 _hasFinishedCounting = false;
geotec 0:157c2fddaa68 59 }
geotec 0:157c2fddaa68 60
geotec 0:157c2fddaa68 61 void PulseCounter::stop()
geotec 0:157c2fddaa68 62 {
geotec 0:157c2fddaa68 63 LPC_TIM2->TCR = 0; // Timer2 stop
geotec 0:157c2fddaa68 64 NVIC_DisableIRQ(TIMER2_IRQn); // disable capture interrupt
geotec 0:157c2fddaa68 65
geotec 0:157c2fddaa68 66 _hasFinishedCounting = true;
geotec 0:157c2fddaa68 67 }
geotec 0:157c2fddaa68 68
geotec 0:157c2fddaa68 69 void PulseCounter::counterArray(int* counterArray, int counterArrayLength)
geotec 0:157c2fddaa68 70 {
geotec 0:157c2fddaa68 71 int i = 1;
geotec 0:157c2fddaa68 72 if(_hasFinishedCounting == true) {
geotec 0:157c2fddaa68 73 while(i <= _pulseCountArrayLength) {
geotec 0:157c2fddaa68 74 *counterArray = _pulseCountArray[i];
geotec 0:157c2fddaa68 75 counterArray++;
geotec 0:157c2fddaa68 76 i++;
geotec 0:157c2fddaa68 77 if (i > counterArrayLength) {
geotec 0:157c2fddaa68 78 // parameter counterArray has less elements than pulseCountArray. Stop copying elements.
geotec 0:157c2fddaa68 79 break;
geotec 0:157c2fddaa68 80 }
geotec 0:157c2fddaa68 81 }
geotec 0:157c2fddaa68 82 } else {
geotec 0:157c2fddaa68 83 // User didn't call stop() before reading pulseCountArray - prevent simultaneous read and write on array. Just return zero array.
geotec 0:157c2fddaa68 84 while(i <= _pulseCountArrayLength) {
geotec 0:157c2fddaa68 85 *counterArray = 0;
geotec 0:157c2fddaa68 86 counterArray++;
geotec 0:157c2fddaa68 87 i++;
geotec 0:157c2fddaa68 88 if (i > counterArrayLength) {
geotec 0:157c2fddaa68 89 // parameter counterArray has less elements than pulseCountArray. Stop copying elements.
geotec 0:157c2fddaa68 90 break;
geotec 0:157c2fddaa68 91 }
geotec 0:157c2fddaa68 92 }
geotec 0:157c2fddaa68 93 }
geotec 0:157c2fddaa68 94
geotec 0:157c2fddaa68 95 // if parameter counterArray has more elements than pulseCountArray. Fill up with zeros.
geotec 0:157c2fddaa68 96 if(counterArrayLength > _pulseCountArrayLength) {
geotec 0:157c2fddaa68 97 while(i <= counterArrayLength) {
geotec 0:157c2fddaa68 98 *counterArray = 0;
geotec 0:157c2fddaa68 99 counterArray++;
geotec 0:157c2fddaa68 100 i++;
geotec 0:157c2fddaa68 101 }
geotec 0:157c2fddaa68 102 }
geotec 0:157c2fddaa68 103 }
geotec 0:157c2fddaa68 104
geotec 0:157c2fddaa68 105 void PulseCounter::_triggerInterrupt()
geotec 0:157c2fddaa68 106 {
geotec 0:157c2fddaa68 107 instance->_arrayPointer++; // increment array pointer
geotec 0:157c2fddaa68 108 wait_us(1); // incrementing pointer needs a little time
geotec 0:157c2fddaa68 109 *instance->_arrayPointer = LPC_TIM2->CR0; // store capture time in eventTimeCount-Array
geotec 0:157c2fddaa68 110
geotec 0:157c2fddaa68 111 LPC_TIM2->TCR = 0x2; // Timer2 count reset
geotec 0:157c2fddaa68 112 LPC_TIM2->TCR = 0x0; // Timer2 disabled
geotec 0:157c2fddaa68 113 LPC_TIM2->TCR = 0x1; // Timer2 enabled
geotec 0:157c2fddaa68 114
geotec 0:157c2fddaa68 115 instance->_triggerCounter++;
geotec 0:157c2fddaa68 116 if (instance->_triggerCounter > _pulseCountArrayLength) {
geotec 0:157c2fddaa68 117 instance->_arrayPointer = &instance->_pulseCountArray[0];
geotec 0:157c2fddaa68 118 instance->_triggerCounter = 0;
geotec 0:157c2fddaa68 119 }
geotec 0:157c2fddaa68 120
geotec 0:157c2fddaa68 121 LPC_TIM2->IR = 0x10; // clear interrupt
geotec 0:157c2fddaa68 122 }
geotec 0:157c2fddaa68 123