Arm Mbed OS support forum

Some digitalin digitalout pins not working on Nuvoton M453

I am using a custom board as the NuMaker PFM-M453 is not available for purchase. I’ve double checked the schematic and don’t think I’ve made any mistakes, although I am using an IC with fewer pins, the M453LG6AE.

Some example code I’ve tried in Mbed studio and with the online complier.

#include "mbed.h"
DigitalIn sw1 (PD_2);
DigitalOut ledR(PC_1);
DigitalOut test(PE_10);
int main()
    test = 1; 
    while(1) {
        ledR = sw1;

I am not getting output from PE_10. I’ve tried PE_10 & PE_11 as inputs and outputs. Output is always at zero volts and inputs read 0 even when voltage is applied.
PC_1 and PD_2 both work properly as do all the other PC and PD pins that I’ve tried.

I don’t know if it makes any difference, but I am not sure the the PE10 & PE11 pins are connected to anything. Is it possible they just aren’t configured for mbed? I don’t get a fault or complier error though.

I’ve also tried this, but get 0 for both values even when voltage is applied.

#include "mbed.h"
DigitalIn toggle_a(PE_11);
DigitalIn toggle_b(PE_10);
int main() {
  while (true) {
    fprintf(pc, "%d ",;
    fprintf(pc, "%d \n",;