Tool/software: Linux
I have a board where a USB power enable line is connected to GPIO pin 113.
I have been trying to toggle this line.
I have been doing this in u-boot, as shown below.
#define LCD_5V5_ENABLE_GPIO 156
#define USB_PWR_GPIO 113
int result;
unsigned long read_res;
gpio_request(LCD_5V5_ENABLE_GPIO, "");
result = gpio_request(USB_PWR_GPIO , "");
printf("gpio_export result %x\n",result);
gpio_direction_output(LCD_5V5_ENABLE_GPIO, 0);
gpio_direction_output(USB_PWR_GPIO, 1);
printf("gpio_direction_output result %x\n",result);
read_res = *((unsigned long *)&gpio4_base->oe);
printf("4 OE %lx\n",read_res);// JJTEMPgpio_set_value(LCD_5V5_ENABLE_GPIO, 1);
gpio_set_value(LCD_5V5_ENABLE_GPIO, 0);
gpio_set_value(USB_PWR_GPIO, 0);
What we have found is that changing the value of gpio_156 in the u-boot code is reflected on the pin. Changing the value of gpio_113 in an identical manner is not reflected on the pin.
Other interesting information, is that the value "read_res", which contains the contents of the OE register for gpio bank 4 , gets set to 0xFFFDFFFF, which is correct for setting gpio113 to output enable The calls to gpio_direction_output and gpio_set_value both return success (0).
I am concerned because of table 25-5 in the AM/DM37x Technical Reference Manual which specifically seems to state that pins 115-112 are input only. Is this correct? Can these pins never be used as output pins?
