flashing " L " and " TX " on Arduino R3 when pluged in

Trying to help grandson download and install Arduino R3 . Installed the Arduino software and the drivers as per the instructions ( I hope ) but when I pluged the board into the usb port the " L " and " TX " leds both blink off and on. Installed on my new computer with windows 10

The "L" LED blinking means pin 13 is being alternately turned HIGH and LOW. This is normal with a new board, it's just some code that shows everything is working.

The "TX" LED blinking means the Arduino is sending something via Serial (Serial.print(), etc.). That is not normal for a new board but it would be normal if a sketch was loaded that has Serial output (as many do).

Neither of these indicate a problem. My recommendation is to just carry on. If you do encounter a problem then come back here and we'll help you out. Otherwise, enjoy!

1 Like

chickenhawk:
Our first sketch was to be " blinking an led " Will the leds stop blinking when we load our first sketch?

It depends on the sketch. If the sketch is setting pin 13 HIGH and LOW then the "L" LED will blink. If the sketch is printing to Serial then the "TX" LED will blink. If you do this:

  1. Select your Arduino board type from the Arduino IDE's Tools > Board menu.
  • Select the COM port of your Arduino board from the Arduino IDE's Tools > Port menu.
  • Select File > New from the Arduino IDE's menus.
  • Select Sketch > Upload from the Arduino IDE's menus.

Then once the upload finishes there should be no blinking LEDs.