Hi,
I got a BBB.
I connected a LED to its GPIO1_16 pin, which I tried to turn on and off
using the GPIO configuration in the code below.
For some reason the LED does not turn ON.
When I use the same GPIO pin, but using the Virtual File System code to
turn on the LED, it works.
Therefore I guess i'm missing something with the below code.
Do you spot any problem?
Thanks a lot.
#define GPIO1_BASE 0x4804C000 // Start Address
#define GPIO1_END 0x4804D000 // End Address
#define GPIO1_SIZE GPIO_END - GPIO_BASE
#define GPIO_OE 0x0134 // Offset
#define GPIO_DATAOUT 0x013C // Offset
#define GPIO1_16 16
int main(int argc, char** argv)
{
volatile unsigned int *reg_base, *reg_oe, *reg_out;
unsigned int value;
int fd;
//open mem file for Read and Write
fd = open("/dev/mem", O_RDWR);
if (fd == -1)
{
perror("Unable to open /dev/mem");
exit(EXIT_FAILURE);
}
/* LED Setup and Turn-on */
reg_base = mmap(0, GPIO1_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd,GPIO_BASE
);
//Set GPIO to Output
reg_oe = (volatile unsigned int*)(reg_base + GPIO_OE);
value = *(reg_oe);
value &= ~(1 << GPIO1_16);
*(reg_oe) = value;
//turn on GPIO
reg_out = (volatile unsigned int*)(GPIO1_16 + GPIO_DATAOUT);
value = *(reg_out);
value |= (1 << GPIO1_16);
*(reg_out) = value;
return 0;
}
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