File content as of revision 0:c5c22fd71be8:

/* This program uses Christopher Hasler motor library to derive DC motors */

#include "mbed.h"
#include "motordriver.h"

// Array of Motor type objects to define 4 motors for two bots.
Motor M[]= {Motor(p25, p9, p8, 1), Motor(p26, p11, p10, 1), Motor(p21, p13, p12, 1), Motor(p22, p15, p14, 1)};
// Array acc defines 4 analogin type objects to detect inputs of accelerometer.
AnalogIn acc[]= {p16, p17, p19, p18};
/*@update reads recent values from accelerometer and uses them to control motors
  @param 'a' tell for which bot the vales should be updated( a=0 for 1st bot and a=2 for 2nd bot)
*/
int update(int a)
{
    float offx=0, offy=0, map=0, turnp=0, turnn=0;
    /*output votage of accelerometer at x and y outs when x=0 and y=0;
      turnp and turnn specifies the positive and negative voltage difference(CurrentVoltage - offset) detected from offset value when accelerometer is tilted.
      I will be using turnp and turnn as the minimum required voltage difference(ie, the minimum required tilt) to turn the bot.
      The value below are default ones for my accelerometer
    */
    if(a==0) {
        offx=0.340;
        offy=0.340;
        turnp=0.032;
        turnn=0.055;
        map=14.68;
    } else if(a==2) {
        offx=0.350;
        offy=0.440;
        turnp=0.040;
        turnn=0.045;
        map=13.40;
    } else
        return(-1);  // return -1 as error when update is called with unexpected argument value
    float s=0, st=0; 
    s=acc[a+1].read();
    s=(s-offy)*map; // multiply by 'map' to linearly map difference (s-offy) to euivalent scale on 0 to 1 so that s can be used as speed
                    // (s=0 for (s-offy)=0 and s=1 for max[(s-offy)] )
    st=acc[a].read();
    st=st-offx;
    if(st>0 && abs(st)>turnp) {  // checking whether to turn or not ( st>0: right turn and st<0: left trun)
        M[a].speed(0);
        M[a+1].speed(1);
    } else if(st<0 && abs(st)>turnn) {
        M[a].speed(1);
        M[a+1].speed(0);
    } else {    // if no turn input then run both motors with speed s
        M[a].speed(s);
        M[a+1].speed(s);
    }
    return 1;
}

int main()
{
    while(1) {
        update(0);  // Calling update for first bot(a=0) and second bot(a=2)
        update(2);
        wait(0.2);
    }
}