Strange behaviour of R4 Minima

Official Hardware UNO Family UNO R4 Minima
1

Hi to all,

PXL_20240209_182709045
PXL_20240209_1827090451677×2236 223 KB

As you can see from the picture, the TX and RX pins of this Arduino R4 Minima are on. Another strange thing is the ADC always shows 0 from every channel. Do you know why?
I uploaded the Blink example and the built-in led works normally.

2

Are you aware that the R4 Unos have 2 hardware UARTs ? One is used by the Serial monitor and to upload code and is not connected to pins 0 and 1.

The other is used by the Serial1 interface and uses pins 0 and 1

So, when you say

that is not quite true

3

I am aware of this. I also burnt the bootloader again, but it didn't resolved anything. As you know normally the TX and RX pins doesn't glow on R4 Minima when a code is uploaded or some data is exchanged through the serial. There are some topic about this issue. Moreover in the blink example there is no data exchange

4

Hi @the_marox666.

Did the RX and TX LEDs remain on while the board was running the "Blink" sketch?

5

Yes, with all the sketches. I have not tried programming the board low-level to turn off manually the LEDs.

6

Can you please try the following code and let me know if this breaks the solid glow behavior that you have been observing? If not can you please share the core version you have been using?

void setup() {
pinMode(22, OUTPUT); //TX LED.
}
void loop() {
digitalWrite(22, HIGH);
delay(500);
digitalWrite(22, LOW);
delay(500);
}
7

I have just uploaded the sketch. The LEDs remain on. The core version is the same as here https://github.com/arduino/ArduinoCore-renesas/tree/main/bootloaders