Confusion with Nano pin numbering

Hi everyone. I am confused by the numbering of the digital pins on the Arduino Nano , on some diagrams, they are : D1(Tx), D0(Rx), D2, D3,.....D12 then we get others with to my mind the correct sequence: D0(Tx), D1(Rx)........D12, is there an official diagram showing which is correct? In one tutorial they have a diagram with D0(Tx) D1(Rx), ....D12 but in the description box they have D0 as Rx and D1 as Tx.
Thanks in advance.

Have seen many different pin out schematics for Nanos.

It’s best to write simple code to toggle a pin hunt the pin down with a LED and resistor.

Do all the digital and analog pins then document your results.

My NANO agrees with the following layout.


TX1 = Data Transmission Pin from the UART Port.
1 after (TX) says that TX-pin is connected with PD1-pin of the MCU. In the Arduino IDE, PD1-pin is recognized as DPin-1 (Digital Pin 1 = D1).

The meaning similar to above is also applies for RX0-pin.

Thanks guys.

At power up (default), are these not digital IO pins?
D0 - D7, D8- D13, A0 - A5 in NANO;
0 - 7, 8 - 13, A0 - A5 in UNO.


Was just using simple language that most new people would recognize especially looking at the silk screening on the PCB.

And of course, A0 to A5 can be referenced as digital pins 14 to 19.

Might be easier to turn on internal pull-ups and use a wire to ground accessing pins with digital read and printing to serial monitor.

You could show the OP one of your great schematics.

The following diagram (Fig-1) shows the use of external pull-down and (built-in) internal pull-up resistors. (Use only one and not both at the same time.)

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