File content as of revision 2:b88fecb5232c:

//lab 2_4_1_Modified.
// Modify the code so that the for loop parameters are variables which can be initialised at the start of the program
// and modified in the while loop to produce a different sound second time around.
#include "mbed.h"

DigitalIn fire(p14); // centre pin of joystick.
PwmOut spkr(p26); // speaker output
int b = 1; // base time for pwm output. this will be divided by the value of 'r'. This will increment up by 10 after first loop.
int r = 100; // base value for the increment of float 'i'. This is used in the PWM calculation, and will increment up by 10 after the first loop. 
int c = 0; //counter on loop.
int main() {
    while(c < 2) { // only repeat loop twice (c will increment after each pass), once c !<2 the program will stop.
        for (float i=2000.0; i<10000; i+=r) { // increment i by 'r' each loop if the value at the start of the loop is less than 1000
            spkr.period((b)/i); // base time/i
            spkr=0.5;
            wait(0.1);
    }
    spkr=0.0;
    b += 10;// increment b by +10
    r += 10; // increment r by +10
    c +=1;// increment count by one.
    printf("Count is %i \n\r", c); // only for display purposes during testing.
    while(!fire) {}
    }
}