MAX30102 with Nordic nRF52840 DK

Wiring for the MAX30102 heart rate + SpO2 on the Nordic nRF52840 DK (nRF52840-QIAA, 3.3 V logic), chosen with the same pin rules BoardPilot uses: default buses first, and no pins that are used for flash, USB, the debugger or booting.

Wiring

MAX30102 pin	Role	Nordic nRF52840 DK pin	Notes
VIN	Power	5V
SDA	I2C data (SDA)	P0.26
SCL	I2C clock (SCL)	P0.27
INT	Interrupt	P1.03
IRD	Not wired to the board	not connected	IR LED output. Leave unconnected
RD	Not wired to the board	not connected	Red LED output. Leave unconnected
GND	Ground	GND

Check before you power it on

Supply: 5 V from the 5V pin.
I2C uses the board’s default pins P0.26 (SDA) and P0.27 (SCL). Most modules include pull-up resistors; if the part is not found, check them and swap-test SDA/SCL.
To make sure it is the real chip, read register 0xFF: a genuine part answers 0x15.

Test code (Arduino)

#include <Wire.h>

void setup() {
  Serial.begin(115200);
  Wire.begin();  // SDA = P0.26, SCL = P0.27 (the board's default I2C pins)
  Wire.beginTransmission(0x57);
  bool found = Wire.endTransmission() == 0;
  Serial.println(found ? "MAX30102 heart rate + SpO2 found at 0x57" : "Not found: check power, GND and SDA/SCL");
}

void loop() {}

Arduino board: adafruit:nrf52:pca10056. Plug USB into the port on the short edge (interface MCU, J2) and set the power switch to ON; before the first Arduino sketch, burn the Adafruit bootloader and SoftDevice once.

Questions

Which Nordic nRF52840 DK pins do I use for the MAX30102?

VIN → 5V, SDA → P0.26, SCL → P0.27, INT → P1.03, GND → GND.

Does the MAX30102 work with the Nordic nRF52840 DK at 3.3 V?

Yes: the MAX30102 runs at 3.3-5 V and the Nordic nRF52840 DK uses 3.3 V signals, so no level shifting is needed.

What is the I2C address of the MAX30102?

0x57. An I2C scan (BoardPilot does it for you) shows which one your module uses.

BoardPilot checks this wiring in 3D as you build it, and finds crossed or missing wires on the real board.

Download BoardPilot

Full Nordic nRF52840 DK pinout · MAX30102 heart rate + SpO2: all pins and data

The MAX30102 on other boards

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