Difference between revisions of "EVM LED Blinking.c"

Revision as of 22:34, 21 May 2007

/**********************************************************************

• EVM_LED_BLINKING.C
• Simple program to blink the LEDs on the DaVinci
• EVM using the the LED port expander PCF8574A at I2C Slave Address 0x38.
• I2C Support and I2C device interface must be turned on in the kernel.
• • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • /

1. include <stdio.h>
2. include <sys/types.h>
3. include <sys/stat.h>
4. include <fcntl.h>
5. include <stdlib.h>
6. include <unistd.h>
7. include <string.h>
8. include <sys/ioctl.h>
9. include <errno.h>
10. include <signal.h>

1. define I2C_DEVICE "/dev/i2c/0"
2. define I2C_DEV_ADDR 0x38
3. define I2C_SLAVE 0x0703

int main() {

       int i2c_fd;

       int state = 0;
       unsigned char val = 0x00;

       int ret;

       struct timespec req =
       {
               .tv_sec = 0,
               .tv_nsec = 100000000,
       };

       if((i2c_fd = open(I2C_DEVICE,O_RDWR)) < 0)
       {
               printf("Unable to open the i2c port!\n");
               exit(1);
       }

       if(ioctl(i2c_fd, I2C_SLAVE, I2C_DEV_ADDR)== -1)
       {
               close( i2c_fd );
               printf("Unable to setup the i2c port!\n");
               exit(1);
       }

       do
       {
               val <<= 1;
               val |= 0x01;

               if(val == 0xFF)
                       val = 0xFE;

               write( i2c_fd, &val, 1);

        } while (!nanosleep (&req, NULL));

       close ( i2c_fd );
       printf ("End.\n");
       return 0;

}