Hi,
Thanks!
it was said there to change the Pad Control Register,
However, it didn't see how one changes this Register.
How is it accessed please?
Thank you.
On Wednesday, February 12, 2014 2:14:38 PM UTC+2, matt wrote:
>
> 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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