Unable to control B Series Eval Board GPIO

Hi all!

I'm using a B404X on a B Series Eval Board and have been unable to control the GPIO to blink an LED.

My code:

int led1 = D6;
int led2 = D7; 

void setup() {
  pinMode(led1, OUTPUT);
  pinMode(led2, OUTPUT);

void loop() {
  digitalWrite(led1, HIGH);
  digitalWrite(led2, HIGH);
  digitalWrite(led1, LOW);
  digitalWrite(led2, LOW);

My LED wiring:

LED + to PWM2 (D6) on the Eval Board through 220 Ohm resistor
LED - to Eval Board GND

What I've tried:

  • Confirmed that my LED circuit is working
  • Plugged the LED + into D7 (which is connected to the LED on the board, and here it blinks alongside the LED on the board)
  • Multiple other pins on the GPIO

Unfortunately, I haven't been able to get the LED to blink on any pin, outside of D7.

Any ideas what I'm doing wrong?


Could this be your issue?

If you also have that jumper set, the state of the detect pin on the SD card slot might interfere with the level you are setting via digitalWrite().


Thanks for the quick reply @ScruffR

Unfortunately my board doesn't have this jumper (I have the M.2 SOM EVAL BOARD V1.1).

This also doesn't seem to be a D6 specific issues, since D5, D4 etc. also don't work.

To add another wrinkle to this, the A0, A1, etc. pins are working properly.

Is my board defective?

@ScruffR you were right. It's the jumpers. They're different on my board but upon removing them, the GPIO pins now work as intended. Thanks for the help.

I think it would be useful to call this out on the docs, which I read before I came here: B Series Evaluation Board | Reference | Particle

It's not clear from these that you HAVE to remove the jumpers to use the GPIO.

Thanks again!

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Good catch @ScruffR :smile:

@west2788 Happy yo hear your problems have been resolved. It kept me busy for a couple of days :see_no_evil:

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