Non-functioning onboard LED

Official Hardware Nano Family Nano R4
1

Got a brand new Nano R4 today and cannot get the onboard orange LED to work. Tried the blink sketch to no avail. RGB LED works fine. The only other R4 board I have is a Minima which I received during the beta program.

Cross-referencing the schematic with the core source code, LED_BUILTIN resolves to digital pin 22, which is pin P204 on the chip. So that’s correct.

Maybe I just got a bad one. Not a problem as I have no real need for it but I just wanted to make sure I’m not going mad. It would be handy to indicate bootloader mode though.

2

Do you have any external circuit connected to the board ?

3

Nope. It’s just dangling from a USB cable connected to my laptop.

4

Can you get to the LED with a voltmeter to measure the voltage? Could be a bad LED, bad resistor, bad thru-hole connection on the board, etc.

5

The single color and RGB are mentioned in section 2.8 (pg 7 of 20)
The RGB shows up as "DL1" in the table, pg 14 of 20, but no further mentions of the single color ('P204').

For some reason they didn't associate it with "D13", I guess.

https://docs.arduino.cc/resources/datasheets/ABX00142-datasheet.pdf

6

Since the Renesas RA4M1 microcontroller has more I/O pins than the number of I/O pins on the Nano's headers, it was possible to use a dedicated pin for the built-in LED. Doing that allows the LED to be used without having to give up using pin 13 for other purposes. This is especially useful when you consider that pin 13 is the SCK pin of the SPI bus, and thus often in use.

7

I opened my Nano R4.
(FWIW - I don't like the new box style).
Where is "22" mentioned in the write-up? It was mentioned by the OP.
The on-board (built-in) LED blinks both ways --

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

void loop()
{
  digitalWrite(LED_BUILTIN, HIGH);
  delay(500);
  digitalWrite(LED_BUILTIN,LOW);
  delay(2000);
}

void setup() 
{
  pinMode(22, OUTPUT);
}

void loop() 
{
  digitalWrite(22, HIGH);
  delay(500);
  digitalWrite(22, LOW);
  delay(2000);
}

It transitions dim - bright - dim -...
during the upload.

8

Serial.println(LED_BUILTIN);

22

I guess mine must have failed. It’s difficult to test during assembly unless you can integrate the process with a camera to detect the LED illumination.

9

@sharp5 said they found the pin mapping in the source code. You can see it here:

(the Arduino pin number is the index of the g_pin_cfg array)

The LED_BUILTIN macro is defined here:

10

You could also just print LED_BUILTIN to the serial monitor to see the PIN number.

11

If you are using Arduino IDE 2.x, you can also just hover the mouse pointer over a reference in the sketch. The IDE will then show you the value. Likewise, you can right click on it, then select "Go to definition" from the context menu to open the file containing the definition in a tab in the Arduino IDE editor.

12

Hello sharp5,

Could you please let me know if the onboard LED works when running the Blink example: IDE > File > Examples > 01.Basics > Blink? Also, the onboard LED should light up during sketch upload.

If it still doesn’t work, you can contact support directly via the form at https://www.arduino.cc/en/contact-us/.

Best regards,