CMUcam for line following

Using the CMUcam on your robot is easy. This tutorial will detail using the CMUcam1.
Here is the CMUcam manual: http://www.seattlerobotics.com/CMUcamManualv15A.pdf

First apply power to the CMUcam as shown in this diagram:

Then connect the Data wires as shown in this diagram. Be sure to remove the Max232 chip.

Connect the GND wire of the CMUcam to a GND pin on your microcontroller. Connect the SX28 Transmit pin to your Rx pin of the microcontroller( on the Axon I chose to use the Rx of UART0). Connect the SX28 Receive pin to your Tx pin of the microcontroller (on the Axon I chose the Tx of UART0).

Now that the electrical connections are set up , we move on to programming.

NOTE: The following code was made for the Axon microcontroller , but can easily be adapted.

UART Initialization:

uartInit();  // initialize the UART (serial port)

    uartSetBaudRate(0, 115200); // set UARTE speed, for Bluetooth  , this is the UART port
 

CMUcam Initialization

void CMUcam_Initialize(void)

    {

    rprintfInit(uart0SendByte);//change UART to CMUcam

    rprintf("RS");  // Reset CMUcam

    delay_ms(500);  // wait 500 milliseconds

    rprintf("cr 18 44"); // Set CMUcam to AutoExposure

    delay_ms(500);  // wait 500 milliseconds

    rprintf("RM 1");  // Set CMUcam to Raw Serial Mode

    delay_ms(500);   // wait 500 milliseconds

    rprintfInit(uart1SendByte);//change UART to USB

    rprintf("CMUcam Initialized");  // send out the message through USB

    }

 

Set Tracking of CMUcam

rprintfInit(uart0SendByte);

rprintf("TC 90 250 0 20 0 20");  // set tracking to this specific color 
// format is minRed maxRed minGreen maxGreen minBlue maxBlue

delay_us(500); // wait 500 microseconds

Get Tracking Data

int CMUcam_MiddleMass(void) //echos # of characters expected for each command

{

int temp;   // set up temporary variable

    int counter=0;  //set the counter to 0

    int echo_counter=0; // set the echo_counter to 0

    int temp1;



    rprintfInit(uart1SendByte);//change UART to bluetooth

    temp = uart0GetByte();  // Get a Byte

    while (temp != 255) {    // Keep on getting new bytes until the byte = 255

        temp = uart0GetByte();

    }

    rprintf("Start= %d  ",temp);

    temp = uart0GetByte();  // Get a Byte

    while (temp != 77) {    // Keep on getting new bytes until the byte = 'M'

        temp = uart0GetByte();

    }   

    rprintf("M= %d  ",temp);



    echo_counter = 8; // expect 8 bytes ( 0 thru 7)

        while(1) {

            temp=uart0GetByte();//returns -1 if no data present

       

            response[counter]=temp;//store values into an array

            counter++;  // add one to "counter" array

   

                if(counter == echo_counter)  // once the counter equals the echo_counter        

                {

                // successfully captured the entire M packet

                uartFlushReceiveBuffer(0);//flush out receive camera buffer to stop phase shifting

                delay_us(100);

                         

                temp1 = response[0];

                rprintf("MiddleMassX= %d  ",temp1);


            temp1 = response[1];

                rprintf("MiddleMassY= %d  ",temp1);
 
          temp1 = response[2];
        rprintf("MinimumX= %d  ",temp1);
         temp1 = response[3];

                rprintf("MinimumY= %d  ",temp1);
            temp1 = response[4];

                rprintf("MaximumX= %d  ",temp1);


                temp1 = response[5];

                rprintf("MaximumY= %d  ",temp1);
           temp1 = response[6];

                rprintf("Pixels= %d  ",temp1);
            temp1 = response[7];

                rprintf("Confidence= %d  ",temp1);


                return response[0]; // return MiddleMass of X axis

                } //endif



        } // end while

} // end sub

Sample Program

int data;

CMUcam_Initialize();  // Initialize CMUcam

rprintfInit(uart0SendByte);



rprintf("TC 90 250 0 20 0 20");  // set tracking to this specific color 
// format is minRed maxRed minGreen maxGreen minBlue maxBlue


delay_us(500); // wait 500 microseconds
while(1) {
data = CMUcam_MiddleMass();   // get the MiddleMass value
if (data > 40) {
// do stuff, turn left, etc.
} //end if 


if (data <40)>
// do stuff, turn right, etc.
} // end if 
} //end while
 

Heres an example of a robot you can create using my code: