File content as of revision 2:f9ec340630b0:

/* 3pi Example 2

(c) Dr Craig A. Evans, University of Leeds

June 2017

*/

#include "mbed.h"
#include "m3pi.h"

// API objects
m3pi robot;
AnalogIn pot_P(p15);
DigitalIn button_enter(p24);

// Function Prototypes
void init();
void calibrate();

// Main Function
int main()
{
    init();

    // move cursor to position (0,0) - top-left
    robot.lcd_goto_xy(0,0);
    robot.lcd_print("Lab 2",5); // 5 is number of characters in message (max 8)
    robot.lcd_goto_xy(0,1);
    robot.lcd_print("Task 1",6);

    // we will update the motors 50 times per second
    float dt = 1.0/50.0;

    calibrate();  // calibrate the sensors

    while (button_enter.read() == 1) {
        // keep looping waiting for Enter to be pressed
    }
    wait(2.0);  // small delay to allow hands to move away etc.

    // array to store sensor values in
    unsigned int values[5]= {0};

    // set the initial speeds (25% forwards)
    float speed = 0.25;

    // threshold to determine when over line
    float threshold = 0.2;

    // value to increase/decrease speed by
    float power = 0.05;

    // main loop - this runs forever
    while(1) {

        // command robot to read sensors and store values in array
        robot.get_calibrated_values(values);

        // in range -1.0 to 1.0
        float position = robot.calc_line_position(values);

        // number is negative when the line is to the left. Need to turn left
        if (position < threshold) {
            // slow down left, speed up right

            // ADD CODE HERE TO CONTROL MOTORS
        }
        // number is positive when the line is to the right. Need to turn right
        else if (position > threshold) {
            // slow down right, speed up left

            // ADD CODE HERE TO CONTROL MOTORS
        }
        // else over the line
        else {
            // drive straight ahead

            // ADD CODE HERE TO CONTROL MOTORS  
        }

        // wait for a short time before repeating the loop
        wait(dt);

    }
}

// Functions
void init()
{
    robot.init();

    // button is 1 when not pressed and 0 when pressed
    button_enter.mode(PullUp);

}

void calibrate()
{
    // clear previous calibration data
    robot.reset_calibration();

    while (button_enter.read() == 1) {
        // keep looping waiting for Enter to be pressed
    }
    wait(2.0);  // small delay to allow hands to move away etc.

    robot.auto_calibrate();  // run auto-calibration routine

}