Real-Time I/O - BeagleBone - page 539

#include <sys/mman.h>
#include <fcntl.h>
#include <signal.h>

// Defines signal-handling functions (i.e. trap

Ctrl-C)
#include "pushLEDmmap.h"

// Global variables
int keepgoing = 1 ; // Set to 0 when Ctrl-c is pressed

// Callback called when SIGINT is sent to the process (Ctrl-C)
void signal_handler ( int sig ) {
printf ( " \n Ctrl-C pressed, cleaning up and exiting... \n " );
keepgoing = 0 ;

}

int main ( int argc , char * argv []) {
volatile void * gpio_addr ;
volatile unsigned int * gpio_datain ;
volatile unsigned int * gpio_setdataout_addr ;
volatile unsigned int * gpio_cleardataout_addr ;

// Set the signal callback for Ctrl-C
signal ( SIGINT , signal_handler );

int fd = open ( "/dev/mem" , O_RDWR );

printf ( "Mapping %X - %X (size: %X) \n " , GPIO0_START_ADDR ,
GPIO0_END_ADDR ,

GPIO0_SIZE );

gpio_addr = mmap ( 0 , GPIO0_SIZE , PROT_READ | PROT_WRITE , MAP_SHARED ,

fd ,

GPIO0_START_ADDR );

gpio_datain = gpio_addr + GPIO_DATAIN ;
gpio_setdataout_addr = gpio_addr + GPIO_SETDATAOUT ;
gpio_cleardataout_addr = gpio_addr + GPIO_CLEARDATAOUT ;

if ( gpio_addr == MAP_FAILED ) {
printf ( "Unable to map GPIO \n " );
exit ( 1 );

}
printf ( "GPIO mapped to %p \n " , gpio_addr );
printf ( "GPIO SETDATAOUTADDR mapped to %p \n " , gpio_setdataout_addr );
printf ( "GPIO CLEARDATAOUT mapped to %p \n " , gpio_cleardataout_addr );