Manually Bootloading; Ubuntu & Linux Issue Fix - adafruit learning system ItsyBitsy 32u4 Manual

// the setup function runs once when you press reset or power the board
void setup() {
// initialize digital pin 13 as an output.
pinMode(13, OUTPUT);
}
// the loop function runs over and over again forever
void loop() {
digitalWrite(13, HIGH);
delay(1000);
digitalWrite(13, LOW);
delay(1000);
}
And click upload! That's it, you will be able to see the LED blink rate change as you adapt the delay() calls.

Manually bootloading

If you ever get in a 'weird' spot with the bootloader, or you have uploaded code that crashes and doesn't auto-reboot
into the bootloader, click the RST button to get back into the bootloader. The red LED will pulse, so you know that its
in bootloader mode. Do the reset button press right as the Arduino IDE says its attempting to upload the sketch, when
you see the Yellow Arrow lit and the Uploading... text in the status bar.
Don't click the reset button before uploading, unlike other bootloaders you want this one to run at the time Arduino is
trying to upload
Ubuntu & Linux Issue Fix
Note if you're using Ubuntu 15.04 (or perhaps other more recent Linux distributions) there is an issue with the modem
manager service which causes the ATmega32u4 micro to be difficult to program. If you run into errors like "device or
resource busy", "bad file descriptor", or "port is busy" when attempting to program then
issue. (https://adafru.it/sHE)
The fix for this issue is to make sure Adafruit's custom udev rules are applied to your system. One of these rules is
© Adafruit Industries
// turn the LED on (HIGH is the voltage level)
// wait for a second
// turn the LED off by making the voltage LOW
// wait for a second
https://learn.adafruit.com/introducting-itsy-bitsy-32u4
you are hitting this
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