When using the traditional Blink example program, the light blinks as expected. Even when writing from scratch digitalWriteing pin 13 to high and low repeatedly works fine. The problem is when I try to use CircuitPlayground.redLED(false). That has no effect, and the Circuit Playground specific Hello_Blink example doesn't work at all. The LED is just constantly on no matter what I do.

I've looked through the source code for the CircuitPlayground library and it's also using pin 13, and doing essentially the same thing as the traditional blink program.

Not sure what else could be causing this.

This is the Blink sketch that's working:

// the setup function runs once when you press reset or power the board
void setup() {
  // initialize digital pin LED_BUILTIN as an output.

// the loop function runs over and over again forever
void loop() {
  digitalWrite(LED_BUILTIN, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(1000);                       // wait for a second
  digitalWrite(LED_BUILTIN, LOW);    // turn the LED off by making the voltage LOW
  delay(1000);                       // wait for a second

And this is the Hello_Blink sketch that is not working (LED remains on permanently):

#include <Adafruit_CircuitPlayground.h>

void setup() {

void loop() {

Changing HIGH and LOW to true and false does nothing.

I also have noticed two other strange things. The speaker does an audible click when the board resets when using the Hello_Blink sketch (or any other sketch that uses the CircuitPlayground library), as if pin #5 is being held high as well. Also, I added these two lines

pinMode(6, OUTPUT);
digitalWrite(6, HIGH);

to the setup() of both programs and then probed #6 with a multimeter. Pin #6 is not connected to anything. The traditional blink program allows the pin to go high as expected. The CircuitPlayground sketch, however, the pin stays low.

I am using this library with a atmega32u4.


1 Answer 1


This appears to be a bug in the Circuit Playground library. An issue was opened here.


Edit: This indeed was a bug, it is now fixed in the library version 1.8.4.

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