Hello,
My self given task was to get a LED blinking on the Beagleboard.
After getting bored from "echo 0 > brightness" and puzzling together
some pieces of code that I found on the net, I finally got a piece of
plain C code that I can cross compile on a Linux machine and play on
the Beagleboard. The two user LEDs as well as one pin of the extension
connect flash in a 1sec clock with it.
No guarantee for completeness, no guarantee for functionality, but
here it works.
Enjoy!
Günter (dl4mea)
/* Blinking of user LEDs USR0 and USR1 and gpio_157 on Expansion
Connector P2
NOTE: gpio_157 is 1.8V IO, possibly not sufficient for a LED
disconnect user LEDs from Linux
echo none > /sys/class/leds/beagleboard::usr0/trigger; echo none > /
sys/class/leds/beagleboard::usr1/trigger;
compile using
<path_to_cross>/arm-armv6-linux-gnueabi-g++ -static blink.c -o blink
References: OMAP35x Applications Processor, Technical Reference Manual
spruf98u.pdf
*/
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/mman.h>
int main(void)
{
printf ("open file descriptor for PADCONFIG\n");
int fd = open("/dev/mem", O_RDWR | O_SYNC); //O_SYNC makes the
memory uncacheable
if (fd < 0) {
printf("Could not open PADCONFIG memory fd\n");
return 0;
}
// Pad configuration
printf ("map PINCONFIG\n");
volatile ulong *pinconf;
pinconf = (ulong*) mmap(NULL, 0x10000, PROT_READ | PROT_WRITE,
MAP_SHARED, fd, 0x48000000);
if (pinconf == MAP_FAILED) {
printf("Pinconf Mapping failed\n");
close(fd);
return 0;
}
printf ("set pinconfig GPIO\n");
pinconf[0x217c/4] = pinconf[0x217c/4] & 0x0000ffff |
0x00040000; // gpio_149
pinconf[0x2180/4] = pinconf[0x2180/4] & 0xffff0000 |
0x00000004; // gpio_150
pinconf[0x218c/4] = pinconf[0x218c/4] & 0x0000ffff |
0x00040000; // gpio_157
close(fd);
/* -------------------------------------- */
printf ("open file descriptor for GPIO\n");
int gpio_fd = open("/dev/mem", O_RDWR | O_SYNC);
if (gpio_fd < 0) {
printf("Could not open GPIO memory fd\n");
return 0;
}
// GPIO configuration
printf ("map GPIO\n");
volatile ulong *gpio;
gpio = (ulong*) mmap(NULL, 0x10000, PROT_READ | PROT_WRITE,
MAP_SHARED, gpio_fd, 0x49050000);
if (gpio == MAP_FAILED) {
printf ("GPIO Mapping failed\n");
close(gpio_fd);
return 0;
}
printf ("set GPIO config\n");
// Configure GPIO pins on bank 5 as output.
// GPIO 5 is at physical address 0x49056000 = 0x49050000+0x6000
gpio[0x6034/4] &= ~0x20600000; // set low for output
// Also disable the wakeupenable and irqenable intertupts
// GPIO clear_Wakeupenable is offset by 0x80 for each bank
gpio[0x6080/4] = 0x20600000; // 0x1: Clear the corresponding
bit in the GPIO_WAKEUPENABLE register
// GPIO clear_irqenable1 is offset by 0x60 for each bank
gpio[0x6060/4] = 0x20600000; // 0x1: Clear the corresponding
bit in the GPIO_IRQENABLE1 register
// GPIO clear_irqenable2 is offset by 0x70 for each bank
gpio[0x6070/4] = 0x20600000; // 0x1: Clear the corresponding
bit in the GPIO_IRQENABLE2 register
/* -------------------------------------- */
printf ("Toggle Pins\n");
int j=0;
for (j=0; j<10; j++)
{
printf ("j=%u\n", j);
//clear_data_out has offset 0x90
gpio[0x6090/4]=0x20600000;
usleep(500000);
//set_data_out has offset 0x94
gpio[0x6094/4]=0x20600000;
usleep(500000);
}
close(gpio_fd);
}
