sonar.c

example of communication between the Cerebellum 16f877 pic board and the CMUcam

// sonar.c - a simple test to check if i2c works
// this program requires a devantech ultrasound sensor and a Cerebellum
// When this program is running, every time you feed Cerebellum a byte
// on the serial port (e.g. hit the space bar) it will request a sonar
// range reading from the Devantech sonar and return that value to you
// via serial.  You must have your computer connected to Cerebellum at 115200
// baud to try this...

#include "cerebv41.h"
#include "cerebv41.c"

void main() 
{
  char command;
  char data0;

  init_cerebellum();    // configure cerebellum
  ser_init(SER_115200); // start up serial port handling
  i2c_init();		// initialize i2c handling

  // Slight start up delay to allow Cerebellum to set everything in initialization  
  delay_ms(100);

  ser_putstring("Setting up i2c master...\r\n");
  
  delay_ms(250);

  while(1)
    {
	command = ser_rcv_nb();
      if( command != 0  ) // if there is a byte to be read on serial line //
	{
	// Below is the sequence of i2c communications to ask the sonar 	
	// to perform a ping then give us a 1-byte value for the range back
	
	i2c_start();
	i2c_send(0xe0); // Device Address
	i2c_send(0); // Register Addr
	i2c_send(0x51); // Command
	i2c_stop();

	delay_ms(200);

	i2c_start();
	i2c_send(0xe0); // Device Address
	i2c_send(0x03); // Send Register Addr to read from

	i2c_restart();

	i2c_send(0xe1);  //Device Address (+1 because we want to read)
	data0 = i2c_receive(); // Receive the 1 data byte from the sonar
	i2c_nak();  //No ack;
	i2c_stop(); 

	ser_putstring("Value is:");
	ser_writechar(data0);
	ser_putstring("\r\n");
	} // end if (command != 0) //

      delay_ms(2);
    } // end while(1) //

} // end main() //