bunt _ / PulseCounter

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");
}

Files at this revision

API Documentation at this revision

Revision 4:0eb01612bcb2, committed 2013-01-09

Comitter:
geotec
Date:
Wed Jan 09 09:57:21 2013 +0000
Parent:
3:9e7474866e48
Commit message:
bugfix: capture interrupt enabled before start()

Changed in this revision

PulseCounter.cpp Show annotated file Show diff for this revision Revisions of this file 
--- a/PulseCounter.cpp	Tue Jan 08 14:25:02 2013 +0000
+++ b/PulseCounter.cpp	Wed Jan 09 09:57:21 2013 +0000
@@ -50,7 +50,6 @@
     // Set custom method to be called on Timer2 interrupt
     NVIC_DisableIRQ(TIMER2_IRQn);
     NVIC_SetVector(TIMER2_IRQn, (uint32_t)&_triggerInterrupt);
-    NVIC_EnableIRQ(TIMER2_IRQn);
     //
 
     LPC_TIM2->TCR = 0x2;            // Timer2 count reset