Hello
In AM335x (TRM) I have read that every pin has 8 different modes,each pin
has specific register like (conf_gpmc_ad0) that you can change the pin mux
mode from [0:7] . There are specific offsets for the pins from the base
address ((0x44E1_0000) region name (Control Module))
I am able to read these registers correctly but my problem is in changing
the value of these registers.
I used ("chmod 777 pinmode") to change the permissions. but the problem
of writing is still remain
The following is the C code I have used.
#define CONTROLMODST 0x44E10000
#define CONTROLMODED 0x44E11FFF
#define CONTROLMODSIZE (CONTROLMODED - CONTROLMODST)
#define PINREGOFF 0x808
#define SYSBOOT 0x40
#define REV 0x00
#define MODE0 0x0
#define MODE1 0x1
#define MODE2 0x2
#define MODE3 0x3
#define MODE4 0x4
#define MODE5 0x5
#define MODE6 0x6
#define MODE7 0x7
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
int main(int argc, char *argv[]) {
volatile void *start_addr = NULL;
volatile unsigned int *pinreg =NULL;
volatile unsigned int *sysboot =NULL;
volatile unsigned int *rev =NULL;
unsigned int reg;
int fd = open("/dev/mem", O_RDWR);
printf("Mapping %X - %X (size: %X)\n", CONTROLMODST, CONTROLMODED,
CONTROLMODSIZE );
start_addr = mmap(0, CONTROLMODSIZE, PROT_READ | PROT_WRITE,MAP_SHARED,
fd, CONTROLMODST);
pinreg=start_addr+PINREGOFF;
sysboot=start_addr+SYSBOOT;
rev=start_addr+REV;
if(start_addr == MAP_FAILED) {
printf("Unable to map\n");
exit(1);
}
printf("Mux mapped to %p\n", start_addr);
printf("Pinreg mapped to %p\n", pinreg);
// printf("Sysboot mapped to %p\n", sysboot);
// printf("Rev mapped to %p\n", rev);
reg=*pinreg;
printf("reg before changing %p\n", reg);
reg=reg|(reg+(1<<1));
*pinreg=reg;
// printf("reg after changing %p\n", pinreg);
printf("reg after changing %p\n", *pinreg);
// reg=*sysboot;
// printf("reg before changing %p\n", reg);
// reg=*rev;
// printf("reg before changing %p\n", reg);
}
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