Pro Micro nRF52840

Caution

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Tip

When using this board with RIOT, set the BOARD variable to pro-micro-nrf52840 in your Makefile. If you follow the standard RIOT project structure, your Makefile should look like this:

./Makefile

# name of your application
APPLICATION = hello-world

# Change this to your board if you want to build for a different board
BOARD ?= pro-micro-nrf52840

# This has to be the absolute path to the RIOT base directory:
RIOTBASE ?= $(CURDIR)/RIOT

include $(RIOTBASE)/Makefile.include

Support for Pro Micro nRF52840-compatible development boards

Overview

Pro Micro nRF52840 boards are Arduino Pro Micro-compatible development boards based on the nRF52840 SoC. This is a generic board definition that supports multiple variants with compatible pinouts. There are many variants available, including:

• Compatible:

  • Nice!Nano V2 (official, open-source)
  • SuperMini nRF52840
  • ProMicro nRF52840
  • Mikoto
  • 52840nano (more GPIO)

• Similar:

  • nRFMicro
  • BlueMicro

All these boards are largely the same in terms of functionality. They vary slightly in pinouts, LED colors, battery charging capabilities and antenna design. Though the board definition is generic, it follows the most common pinout of the Nice!Nano V2.

This board definition is frequently used for building battery-powered custom wireless keyboards. A comprehensive overview of various compatible variants, including their specific features and known issues, can be found at NRF Micro Wiki - Alternatives.

Hardware

The board is pin-compatible with the Arduino Pro Micro and features:

• nRF52840 SoC with ARM Cortex-M4F CPU
• 1 MiB Flash, 256 KiB RAM
• Bluetooth Low Energy 5.0
• USB-C connector with USB device support (some variants use USB Micro)
• Single board-provided LED (color varies by variant: blue, red, or green)
• Arduino Pro Micro form factor

Pin Layout

The board follows the Pro Micro pinout. The following tables show the complete pin mapping:

Complete Pin Mapping

nRF52840 Pin	Arduino Pin	Function	Notes
P0.08	D0	UART RX	Serial receive
P0.06	D1	UART TX	Serial transmit
P0.17	D2	I2C SDA	I2C0 data line
P0.20	D3	I2C SCL	I2C0 clock
P0.22	D4	GPIO
P0.24	D5	GPIO
P1.00	D6	GPIO
P0.11	D7	GPIO
P1.04	D8	GPIO
P1.06	D9	GPIO
P0.09	D10	GPIO
-	D11	-	Not available
-	D12	-	Not available
P0.15	D13	GPIO	LED
P1.11	D14	SPI MISO	SPI0 MISO
P1.13	D15	SPI SCK	SPI0 SCK
P0.10	D16	SPI MOSI	SPI0 MOSI
-	D17	-	Not available
P1.15	D18	GPIO
P0.02	D19	GPIO
P0.29	D20	GPIO
P0.31	D21	GPIO

Primary Peripherals

Peripheral	nRF52840 Pins	Arduino Pins	Description
UART (USB)			Used for STDIO
UART (Serial)	P0.08, P0.06	D0, D1	RX, TX
I2C0	P0.17, P0.20	D2, D3	SDA, SCL
SPI0	P0.10, P1.11, P1.13	D16, D14, D15	MOSI, MISO, SCK

The color of the LED may vary between board variants.

Flashing, Bootloader, and Terminal

The board uses the Adafruit nRF52 Bootloader. Refer to the Adafruit nRF52 Bootloader documentation for further details on the flashing process.

Example with hello-world application:

make BOARD=pro-micro-nrf52840 -C examples/basic/hello-world flash term

The terminal will connect to STDIO over USB (USB-CDC).