Go Down

Topic: RX diode always ON (Read 7006 times) previous topic - next topic


Hi everyone!

Just today i have received my Leonardo. After some tutorial testing (blink, etc...), the RX diode keeps always ON. And i dont know what it means...

I try to reset the board, unpluged and plug the USB and so on... When I reset the board, the "power diode" turn ON and the "L diode" blinks 2-3 seconds, but after that, the "L diode" turns OFF and the RX´s turns ON.

I can´t upload a new sketch neither.

I have no previous electronical knowledge and i dont know what to do.

Thanks in advance!
Unas veces se gana y otras se aprende.

Nick Gammon

Please post technical questions on the forum, not by personal message. Thanks!

More info:

Nick Gammon

After some tutorial testing (blink, etc...)

Were you able to get blink uploaded? Is that what you are saying?

What version of the Arduino IDE do you have?
Please post technical questions on the forum, not by personal message. Thanks!

More info:

Louis Davis


Sorry. Win7 x32 and IDE 1.0.1

The problem is that the RX diode is always ON, even after reset the board and only with the usb pluged.
Unas veces se gana y otras se aprende.


Excuse my very bad explanation.

The board was working properly. I uploaded some sketches and it works properly. But suddenly when i was uploading a new sketch, it stopped working, the RX diode turns ON and keep lighting and i can´t upload new sketches.

Then i try to reset the board, to re-plug the USB, select a new COM...
Unas veces se gana y otras se aprende.


Try this, from the Leonardo getting started page (http://arduino.cc/en/Guide/ArduinoLeonardo):

These differences affect the way you use the physical reset button to perform an upload if the auto-reset isn't working. Press and hold the reset button on the Leonardo, then hit the upload button in the Arduino software. Only release the reset button after you see the message "Uploading..." appear in the software's status bar. When you do so, the bootloader will start, creating a new virtual (CDC) serial port on the computer. The software will see that port appear and perform the upload using it. Again, this is only necessary if the normal upload process (i.e. just pressing the uploading button) doesn't work. (Note that the auto-reset is initiated when the computer opens the Leonardo's serial port at 1200 baud and then closes it; this won't work if something interferes with the board's USB communication - e.g. disabling interrupts.)


Thank you very much @Nick Gammon, @Louis Davis and @mellis.

I did what mellis posted and everything is OK again. Thank you, and let me excuse again in order to my bad explanation.

Kind regards!
Unas veces se gana y otras se aprende.


Hi All,
I had the same problem with my Pro Micro, I uploaded an example with tone (speakers) and it caused my Arduino to not be able to upload any more, it was stuck on "Send V" and the RX Led was constantly on. I managed to get out of this scary situation by shorting the GND and the RST pins twice consecutively just a fragment before I clicked the upload button on the IDE (it came from the Firmware note, saying how to reset and override the bootloader). I must say that it took me some attempts (~ 5-7 times) until I got the right timing but I did. so for those who have the same issue, don't get desperate and keep trying.

thank you all


Thank u very much @ mellis :) :) :) :)

Go Up

Please enter a valid email to subscribe

Confirm your email address

We need to confirm your email address.
To complete the subscription, please click the link in the email we just sent you.

Thank you for subscribing!

via Egeo 16
Torino, 10131