#3 Arduino Nano 33 BLE - Toggling GPIO pin on Arduino Nano 33 BLE board

The purpose of this program is to toggle the LED connected to the below highlighted pin using Arduino IDE.

The confusion lies for the beginners is how to refer the pin number for the PIN#1 of the JP3 connector in the code. It can be referred as D0 or 0

// Toggle LED connected to pin D0 (RX)

// Works only if Serial1 is not active

const int ledPin = D0;    // RX pin (P0.08 on nRF52840)

//const int ledPin = 0;    // can be referred as 0 as well

void setup() {

  pinMode(ledPin, OUTPUT);  // configure D0 as output

}

void loop() {

  digitalWrite(ledPin, HIGH);   // turn LED ON

  delay(500);                   // wait 500ms

  digitalWrite(ledPin, LOW);    // turn LED OFF

  delay(500);                   // wait 500ms

}

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Below is the pin mapping for the other pins on JP2 and JP3 connector.

Arduino Pin	MCU Pin (nRF52840)	Notes
D0	P1.10	RX
D1	P1.03	TX
D2	P1.11
D3	P1.12
D4	P1.15
D5	P1.13
D6	P1.14
D7	P0.23
D8	P0.21
D9	P0.27
D10	P1.02	SPI CS
D11	P1.01	MOSI
D12	P1.08	MISO
D13	P0.13	SCK / Built-in LED
A0	P0.04
A1	P0.05
A2	P0.30
A3	P0.29
A4	P0.31	SDA
A5	P0.02	SCL
A6	P0.28
A7	P0.03

SCK has built-in LED, that is why we see that both on-board LED and externally connected LED are blinking