main.c

/* CSCI 255 - Final Project: Wall Avoiding Robot
 * Fall 2017
 *
 * Chris O'Neill, Keith Bocian, Sam Croft
 *
 * file: main.c
 * */

#include <msp430.h>

//Function prototypes
void backUp();
void turnRight();
void turnLeft();
void reverse();
void straight();
void turnDelay();


//main
int main() {
    WDTCTL = WDTPW | WDTHOLD;

    P1REN |= 0x20; // Enable resister for pin 1.5
    P1DIR &= ~0x20; // Have resister pull-down (active high)

    P2DIR |= BIT1 | BIT4; // P2.1 and P2.4 for outputs to servo with PWM
    P2SEL |= BIT1 | BIT4; // associate P2.1 and 2.4 with Timer_A1

    P1DIR |= BIT6; // P1.6 - infrared LED output with PWM
    P1SEL |= BIT6; // associate P1.6 Timer_A0

    TA0CCR0 = 26; // Length of period for PWM for timer A0 (1MHz / 38000Hz)
    TA0CCR1 = 13; // 50% duty cycle on infrared LED (P1.6) 50% duty cycle ensures IR LED changes from low to high twice as often in a given period of time as one on a 100% duty cycle, making it easier for sensor to detect these modulations.
    TA0CCTL1 = OUTMOD_7; //Mode7 reset/set
    TA0CTL = TASSEL_2 + MC_1; // Timer SMCLK Mode UP

    TA1CCR0 = 20000; // Length of period for PWM for timer A1
    TA1CCTL1 = OUTMOD_7; // Mode7 reset/set
    TA1CCTL2 = OUTMOD_7; // Mode7 reset/set
    TA1CTL = TASSEL_2 + MC_1; // Timer SMCLK Mode UP

    while(1){
        //If the sensor receives an infrared signal
       if(!(0x20 & P1IN)){
            backUp();
            turnLeft();
        }
        //Else go straight
        else{
            straight();
        }
    }
}

//turnDelay function
//Has the robot continue to turn for 60000 clock cycles
void turnDelay() {
    volatile unsigned int i;

    for(i = 0; i < 60000; i++);
}

//Backup function
//Has the robot go in reverse for 50000 clock cycles
void backUp() {
    volatile unsigned int i;

    for(i = 0; i < 50000; i++) {
            reverse();
    }
}

//Straight function
//Makes the wheels spin forward at the same speed
void straight() {

    //1640 - 360 = 1280
    TA1CCR1 = 1280;

    //1640 + 360 = 2000
    TA1CCR2 = 2000;
}

//Reverse function
//Makes the servo wheels spin in reverse at the same speed
void reverse() {

    //1640 + 360 = 2000
    TA1CCR1 = 2000;

    //1640 - 360 = 1280
    TA1CCR2 = 1280;
}

//This function is not used, but we have it here as an
//  optional feature for later implementation
//Turn right function
//Makes the right wheel spin in reverse
void turnRight() {
    TA1CCR1 = 2000;

    //spin right wheel in reverse
    TA1CCR2 = 2000;

    //Delay to turn right about 90 degrees
    turnDelay();
}

//Turn left function
//Makes the left wheel spin in reverse
void turnLeft() {

    //Make the left wheel spin in reverse
    TA1CCR1 = 1280;
    TA1CCR2 = 1280;

    //Delay to turn left about 90 degrees
    turnDelay();
}