Hi,
I used the following device tree overlay to configure “GPIO1_16” (which is P9-15) to Mode-7 (=GPIO):
`
//file name: BB-gpio-set-00A0.dts
/dts-v1/;
/plugin/;
/ {
compatible = “ti,beaglebone”, “ti,beaglebone-black”;
/* identification */
part-number = “BB-LED”;
version = “00A0”;
/* state the resources this cape uses /
exclusive-use =
/ the pin header uses /
“P9.15”, / GPIO1_16 /
/ the hardware ip uses */
“GPIO1_16”;
fragment@0 {
target = <&am33xx_pinmux>;
overlay {
bb_GPIO1_16_pins: pinmux_bb_GPIO1_16_pins {
pinctrl-single,pins = <
0x40 0x07 /* P9.15 OUTPUT */
;
};
};
};
};
`
Then, I compiled it with dtc, copied the dtbo file to /lib/firmware/,
and performed echo BB-gpio-set > slots
Now, I ran the following Code to turn on GPIO1_16, but the code does not turn it ON.
Why it that please?
`
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#define GPIO1_BASE 0x4804C000
#define GPIO1_END 0x4804CFFF
#define GPIO1_SIZE GPIO1_END-GPIO1_BASE
#define GPIO_OE 0x0134
#define GPIO_DATAOUT 0x013C
#define GPIO_USERBUTTON 7
#define GPIO1_16 16 //GPIO1_16
#define GPIO_SETDATAOUT 0x194
#define GPIO_CLEARDATAOUT 0x190
int main(int argc, char** argv)
{
volatile unsigned int *reg, *reg_base, *reg_clr;
unsigned int value;
int fd = open(“/dev/mem”, O_RDWR);
/* LED0 Setup and Turn-on */
//Set GPIO_OE to Output
reg_base =(volatile unsigned int*) mmap(0,GPIO1_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, GPIO1_BASE);
reg = (volatile unsigned int*)(reg_base + GPIO_OE);
value = *(reg);
value &= ~(1 << GPIO1_16);
*(reg) = value;
//set GPIO_SETDATAOUT to turn LED on
reg = (volatile unsigned int*)(reg_base + GPIO_SETDATAOUT);
value = *(reg);
value |= (1 << GPIO1_16);
*(reg) = value;
return 0;
}
`
