DEN (Digital ENable) is required for digital I/O

Even for alternate I/O pin functions.

diff --git a/main.c b/main.c
index 3588743..4cfd891 100644 (file)
--- a/main.c
+++ b/main.c
@@ -42,6 +42,7 @@ void main_isr() {
        GPIO_PORTA_AFSEL_R = 0x03;
        GPIO_PORTA_DR2R_R = 0x03;
        GPIO_PORTA_PCTL_R = 0x11;
+       GPIO_PORTA_DEN_R = 0x03;
 
        // Set 115200bps
        UART0_IBRD_R = 43;