Vidor 4000 LED_BUILTIN LOW is HIGH

Hardware MKR Family MKRVIDOR4000
1

When I run following blink code it stays 10s on HIGH which is the opposite behavior.

void setup() {
pinMode(LED_BUILTIN, OUTPUT);
}

void loop() {
digitalWrite(LED_BUILTIN, HIGH);
delay(2000);
digitalWrite(LED_BUILTIN, LOW);
delay(10000);
}

I also checked the WifiNina > Ap_SimpleWebServer example and clicking on High link actually turns off the LED and vice versa. I also tried with 0 and 1 instead of LOW and HIGH respectively to see if constant values has changed.

2

Regarding to the schematic the cathodes of the user (RGB) led are driven by control signals (PB08 of SAM D21 is driving "R") whereas the anode is tight to Vcc (+3.3 V).
So the behavior you observe is what is to be expected with this hardware constellation ...

3

Is this intended behavior or hardware bug? I don't expect to see LED off when I set it to be HIGH in my code and vice versa.

4

It's not a bug. Active LOW is quite common. You just need to get used to LOW being a state rather than assuming "HIGH means on".

I generally treat HIGH and LOW as "magic numbers" in my code. Something like this:

const byte LEDonState = LOW;
const byte LEDoffState = HIGH;

void setup() {
  pinMode(LED_BUILTIN, OUTPUT);
}

void loop() {
  digitalWrite(LED_BUILTIN, LEDoffState); 
  delay(2000);                       
  digitalWrite(LED_BUILTIN, LEDonState); 
  delay(10000);
}