IR Proximity Motor Control

The Software
           There are two main portions of code that we are concerned with:

    -The Initializations
    -Forever While Loop



The compiler used for this project is the C18 Compiler Provided Free From Micropchip. The first part of this software initailizes the A/D converter and the PWM module in the PIC.

PIC Initializations For Motor Control

..
...
    /*
    Timer2 Prescalary Details:
    0b00 = Prescalar x 1
    0b01 = Prescalar x 4
    0b10 = Prescalar x 16
    */
    T2CONbits.T2CKPS0 = 0;
    T2CONbits.T2CKPS1 = 0;

    // PWM Frequency = [(period ) + 1] x 4 x TOSC x TMR2 prescaler
    // Tosc = 20 MHz
    // TMR2 Prescalar = 1
    // Period = 128
    // PWM Frequency = (256) x 4 x (1/20,000,000) x 1 = 19.5 KHz
    OpenPWM1( period );

    //Motor Initially Off
    SetDCPWM1( speed_0 );

    // configure A/D convertor
    OpenADC( ADC_FOSC_32 & ADC_RIGHT_JUST & ADC_20_TAD,
    ADC_CH0 & ADC_VREFPLUS_VDD & ADC_VREFMINUS_VSS 
    & ADC_INT_OFF, 0 );
...
..

           This next chunk of code is the forever while loop which controls the motor and LED bar. This loop, takes the sensor input data, evaluates it and then outputs to the LED Bar and Motor depending upon the distance detected.

Forever Control/While Loop

    while(1){
        
        Delay10TCYx( 5 ); // Delay for 50TCY
        ConvertADC(); // Start conversion
        while( BusyADC() ); // Wait for completion
            result = ReadADC(); // Read result

        //Update Motor Speed Setting & LED Bar
        if(result < dist_6cm && result > dist_8cm){
            SetDCPWM1( speed_8 );
            PORTD = 0xFF;
        }
        else if(result < dist_8cm && result > dist_10cm){
            SetDCPWM1( speed_7 );
            PORTD = 0xFE;
        }
        else if(result < dist_10cm && result > dist_12cm){
            SetDCPWM1( speed_6 );
            PORTD = 0xFC;
        }
        else if(result < dist_12cm && result > dist_14cm){
            SetDCPWM1( speed_5 );
            PORTD = 0xF8;
        }
        else if(result < dist_14cm && result > dist_16cm){
            SetDCPWM1( speed_4 );
            PORTD = 0xF0;
        }
        else if(result < dist_16cm && result > dist_18cm){
            SetDCPWM1( speed_3 );
            PORTD = 0xE0;
        }
        else if(result < dist_18cm && result > dist_20cm){
            SetDCPWM1( speed_2 );
            PORTD = 0xC0;
        }
        else if(result < dist_20cm && result > dist_22cm){
            SetDCPWM1( speed_1 );
            PORTD = 0xFE;
        }
        else if(result < dist_22cm){
            SetDCPWM1( speed_0 );
            PORTD = 0x00;
        }

        Delay10KTCYx( 5 ); // Delay for 50TCY
    }

           These are the two main portions of the program. Download the full .c file at the top of the page to see the small things I left out. Give it a compile with the C18 libraries in MPLAB, load the hex file onto the PIC and the system is ready to go!