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 #ifndef MBED_PULSECOUNTER_H
geotec 0:157c2fddaa68 2 #define MBED_PULSECOUNTER_H
geotec 0:157c2fddaa68 3
geotec 0:157c2fddaa68 4 #include "mbed.h"
geotec 0:157c2fddaa68 5
geotec 0:157c2fddaa68 6 const int _pulseCountArrayLength = 20;
geotec 0:157c2fddaa68 7
geotec 0:157c2fddaa68 8 /** Counts pulses on pin29 coming in with a frequency up to 48 MHz. The counter is read (and reset to 0) by rising edge (trigger event) on pin30.
geotec 0:157c2fddaa68 9 * These events can be triggered at a rate up to 9kHz. The counter results are stored in a "circular array" of 20 elements.
geotec 0:157c2fddaa68 10 * ("circular array" = array pointer increments each time a new value is stored into the array; if pointer reaches last element, it is redirected to first element)
geotec 0:157c2fddaa68 11 * */
geotec 0:157c2fddaa68 12 class PulseCounter
geotec 0:157c2fddaa68 13 {
geotec 0:157c2fddaa68 14 public:
geotec 0:157c2fddaa68 15
geotec 0:157c2fddaa68 16 /** Initializer for PulseCounter instance
geotec 0:157c2fddaa68 17 */
geotec 0:157c2fddaa68 18 void init();
geotec 0:157c2fddaa68 19
geotec 0:157c2fddaa68 20 /** Start counter
geotec 0:157c2fddaa68 21 */
geotec 0:157c2fddaa68 22 void start();
geotec 0:157c2fddaa68 23
geotec 0:157c2fddaa68 24 /** Stop counter
geotec 0:157c2fddaa68 25 */
geotec 0:157c2fddaa68 26 void stop();
geotec 0:157c2fddaa68 27
geotec 0:157c2fddaa68 28 /** Read pulse count results into external array. Do not call this method before you called method stop() - otherwise it will return zeros.
geotec 0:157c2fddaa68 29 * @param counterArray = Pointer to array in which the pulse count results should be read into.
geotec 0:157c2fddaa68 30 * @param counterArrayLength = Size of counterArray. Should be 20 or less. If more than 20, remaining elements will be filled with zeros.
geotec 0:157c2fddaa68 31 * @code #include "mbed.h"
geotec 0:157c2fddaa68 32 #include "PwmOscillator.h"
geotec 0:157c2fddaa68 33 #include "PulseCounter.h"
geotec 0:157c2fddaa68 34
geotec 0:157c2fddaa68 35 Serial usbPC(USBTX, USBRX); // sends log messages via USB to PC terminal
geotec 0:157c2fddaa68 36 PwmOscillator pulseGenerator; // generates pulses to be count (48 MHz) on pin p22. Connect this pin to p29 (counter input).
geotec 0:157c2fddaa68 37 PulseCounter pulseCounter; // counts the pulses on pin p29 between trigger events (= rising edges) on pin p30.
geotec 0:157c2fddaa68 38
geotec 0:157c2fddaa68 39 int main()
geotec 0:157c2fddaa68 40 {
geotec 0:157c2fddaa68 41 usbPC.printf("---> start <---\n");
geotec 0:157c2fddaa68 42 pulseGenerator.initWithFrequency(48000000);
geotec 0:157c2fddaa68 43 pulseCounter.init();
geotec 0:157c2fddaa68 44 pulseGenerator.start();
geotec 0:157c2fddaa68 45
geotec 0:157c2fddaa68 46 pulseCounter.start();
geotec 0:157c2fddaa68 47 wait(1); // waiting 1 second for trigger events (pin30: rising edge). Count pulses between trigger events.
geotec 0:157c2fddaa68 48 pulseCounter.stop();
geotec 0:157c2fddaa68 49
geotec 0:157c2fddaa68 50 pulseGenerator.stop();
geotec 0:157c2fddaa68 51
geotec 0:157c2fddaa68 52 // read & print pulseCounter results
geotec 0:157c2fddaa68 53 int pulseCounterResults[20];
geotec 0:157c2fddaa68 54 pulseCounter.counterArray(&pulseCounterResults[0],sizeof pulseCounterResults / sizeof (int));
geotec 0:157c2fddaa68 55
geotec 0:157c2fddaa68 56 for(int i = 0; i < (sizeof pulseCounterResults / sizeof (int)); i++) {
geotec 0:157c2fddaa68 57 usbPC.printf("counter of trigger event %i = %i\n",i,pulseCounterResults[i]);
geotec 0:157c2fddaa68 58 }
geotec 0:157c2fddaa68 59 //
geotec 0:157c2fddaa68 60
geotec 0:157c2fddaa68 61 usbPC.printf(" finished.\n");
geotec 0:157c2fddaa68 62 }
geotec 0:157c2fddaa68 63 * @endcode */
geotec 0:157c2fddaa68 64 void counterArray(int* counterArray, int counterArrayLength);
geotec 0:157c2fddaa68 65
geotec 0:157c2fddaa68 66 private:
geotec 0:157c2fddaa68 67
geotec 0:157c2fddaa68 68 static void _triggerInterrupt();
geotec 0:157c2fddaa68 69 static PulseCounter *instance;
geotec 0:157c2fddaa68 70 bool _hasFinishedCounting;
geotec 0:157c2fddaa68 71
geotec 0:157c2fddaa68 72 volatile int _triggerCounter;
geotec 0:157c2fddaa68 73 volatile uint32_t *_arrayPointer;
geotec 0:157c2fddaa68 74 volatile uint32_t _pulseCountArray[_pulseCountArrayLength + 1];
geotec 0:157c2fddaa68 75 };
geotec 0:157c2fddaa68 76
geotec 0:157c2fddaa68 77 #endif