File content as of revision 0:1fe3a53ac109:

/* timing.cpp api verion 1.01 */
/* wajw  21/03/18  */
//V 1.02 mod to just do period measurement edh 24/03/18
/* Prog to measure period of rotation of flywheel */


/* Software uses Pin 9 as an interrupt to determine rotation period */
/* A ticker is used to give a count of elapsed time */

/* Interrupt occurs on +ve edge of TDC Pulse on pin10 */
/* ISR Stores ticker count value as 'period', resets 'count' and sets flag */

#include "mbed.h"
#include "C12832_lcd.h"
#define counts_per_min 600000 // .1ms clock = 600k pulses minute

//advance degree and RPM data arrays 
static int map[] = {5,5,6,10,15,15,21,25,27,34,38}; // advance angles in degrees BTDC
static int rpm_range[] = {500,600,700,800,900,1000,1100,1200,1300,1400,1500}; //rpm range for which the advance angle should change 

//Global Variables:

volatile int  period = 0, count1 = 0; //this was changed to float to display the period more precisely

volatile int pflag = 0, rpm = 0;

int lag;
int spark_advance; //to be used for the advance degree input

C12832_LCD lcd;

// Function Prototypes:

void Tick1_isr (void);
void TDC_isr (void);
void Spark_on (void); // set the output Spark (p10) high
void Spark_off (void); // set it low
void Ignition(int);

//custom function prototypes
void advance_calculator(int);


// Hardware Definitions:

Ticker Tick; //Tick produces a periodic interrupt
DigitalOut Spark(p10);  //Spark Output to Flywheel Board
InterruptIn tdc(p9);    //Pulse from TDC Sensor on Flywheel Board

Timeout StartSpark; //one-off interrupt to set spark o/p high
Timeout EndSpark; // and this one sets spark low

//Function Declarations:
void Ignition(int lag)
{
    StartSpark.attach_us(&Spark_on, lag) ; // set time of Spark
    EndSpark.attach_us(&Spark_off, lag + 200); //and duration of spark at 200usec
}
    
void Spark_on()
{
    Spark = 1;
}

void Spark_off()
{
    Spark = 0;
}


void Tick1_isr()
//Interrupt cause by Ticker
//Increments count every 100usec
{
     count1++;   
}

void TDC_isr()
 //Interrupt caused by +ve edge on TDC 
 //Captured value = period 
{
    period = count1;    //Capture time since last TDC
    count1 = 0;
    pflag = 1;         // New value of period available
}

//custom functions declaration
void advance_calculator(int rpm)
{
    if(rpm < rpm_range[0])
    {
        spark_advance = 360 - map[0];
    }
    else if(rpm >= rpm_range[0] && rpm < rpm_range[1])
    {
        spark_advance = 360 - map[0];
    }
    else if(rpm >= rpm_range[1] && rpm < rpm_range[2])
    {
        spark_advance = 360 - map[1];
    }
    else if(rpm >= rpm_range[2] && rpm < rpm_range[3])
    {
        spark_advance = 360 - map[2];
    }
    else if(rpm >= rpm_range[3] && rpm < rpm_range[4])
    {
        spark_advance = 360 - map[3];
    }
    else if(rpm >= rpm_range[4] && rpm < rpm_range[5])
    {
        spark_advance = 360 - map[4];
    }
    else if(rpm >= rpm_range[5] && rpm < rpm_range[6])
    {
        spark_advance = 360 - map[5];
    }
    else if(rpm >= rpm_range[6] && rpm < rpm_range[7])
    {
        spark_advance = 360 - map[6];
    }
    else if(rpm >= rpm_range[7] && rpm < rpm_range[8])
    {
        spark_advance = 360 - map[7];
    }
    else if(rpm >= rpm_range[8] && rpm < rpm_range[9])
    {
        spark_advance = 360 - map[8];
    }
    else if(rpm >= rpm_range[9] && rpm < rpm_range[10])
    {
        spark_advance = 360 - map[9];
    }
    else //this computes the angle for any speeds higher than 1500RPM (still same angle as 1500RPM)
    {
        spark_advance = 360 - map[10];
    }
}
    
 
int main()
{ 

//Produce regular clock tick for timing period:
  Tick.attach_us(&Tick1_isr, 100);   //initializes the ticker with period of 100usec
                                  //and attaches it to Tick1 ISR 

   tdc.rise(&TDC_isr); // Generate Interrupt on each TDC pulse
   
   lcd.cls();
   //advance_calculator(rpm); //called for the first time, since rpm is 0, 5 will be assigned to advance angle
      
    while(1) {
       
       
        //spark_advance = 360 - 15; //360(TDC point) - advance angle = spark_advance
       advance_calculator(rpm);
       
       if (pflag == 1) // new timing data?
        {  
            //lag = (period*100)*180/360; // Period is in units of 100usec
            lag = (period*100)*spark_advance/360; // Period is in units of 100usec
            Ignition(lag);
            
            //your code here to calculate rpm
            rpm = (1/(period*100e-6))*60; //1 period = 1*100us(period counter incrments every 100us, this conversion is needed to get the Hz frequency
            
            lcd.locate(0,0);
            lcd.printf("Period(T): %4.2d ms", period/10); // display captured data in ms to match the osciloscope reading 
            lcd.locate(0,11);
            lcd.printf("Speed(RPM): %4.2d ", rpm); // display captured data  
            
            //this is used to print the advance angle for troubleshooting purposes
            lcd.locate(0,22);
            lcd.printf("Advance(deg): %4.2d ", 360-spark_advance); // display captured data  
            pflag = 0; //reset flag 
        }
        
    }
}