NRF52840

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Project NRF52840
Running Arduino with platformio on NRF52840
Status In progress
Contact bertrik
Last Update 2026-01-12

Intro

This page is about getting inexpensive NRF52840 boards to work with Arduino and platformio.

NRF52840 is a nice platform:

  • low-power
  • inexpensive
  • decent amount of flash (1024k), RAM (256k) and CPU cycles (64 MHz)
  • support various radio protocols like zigbee, ble, thread, enhanced shockburst
  • built-in support for quadrature counting
  • can run arduino too

However the eco-system of inexpensive boards is a complicated landscape:

  • AliExpress sellers offer "promicro" and "supermini" board with unclear characteristics
  • LEDs are sometimes swapped (blue = hardware charge, red = software led?)
  • Various firmware upload interface options (which one to use?):
    • Using nrfutil, sends a .zip file containing various parts, over USB-serial
    • Mass storage UF2, activated using the double-reset
    • SWD debug interface (requires soldering!)
  • Confusing situation regarding bootloaders:
    • Most boards seem to come with a modified version of a bootloader meant for another type of board
    • Type of bootloader depends on type of firmware you want to run, "ZMK", Arduino using Arduino IDE, Arduino using platformio
    • Risk of accidentally overwriting the bootloader, with UF2 flash offsets sometimes being absolute, sometimes being relative

Hardware

pinout

The boards I have are the "promicro" and "supermini". These boards look basically identical hardware-wise.

There is a 4-pad connector to program it using SWD (VDD/SWD/SDC/GND). This can be used to write the bootloader for example. The pads have a spacing of 1.5mm.

The blue LED appears to flash independently of software, this is probably the charge circuit behaving randomly without a battery present. The red LED appears to be under software control.

Pinout/schematic: https://nicekeyboards.com/docs/nice-nano/pinout-schematic

bootloader

The INFO_UF2.TXT says (after double-tap reset): 

 UF2 Bootloader 0.6.0 lib/nrfx (v2.0.0) lib/tinyusb (0.10.1-41-gdf0cda2d) lib/uf2 (remotes/origin/configupdate-9-gadbb8c7)
 Model: nice!nano
 Board-ID: nRF52840-nicenano
 SoftDevice: S140 version 6.1.1
 Date: Jun 19 2021

The CURRENT.UF2 file is 1.4 MB

Kernel log says: 

[509372.005339] usb 1-2.3: new full-speed USB device number 96 using xhci_hcd
[509372.132351] usb 1-2.3: New USB device found, idVendor=239a, idProduct=00b3, bcdDevice= 1.00
[509372.132361] usb 1-2.3: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[509372.132364] usb 1-2.3: Product: nice!nano
[509372.132366] usb 1-2.3: Manufacturer: Nice Keyboards
[509372.132368] usb 1-2.3: SerialNumber: 98D93A272A6CCC7D
[509372.187474] cdc_acm 1-2.3:1.0: ttyACM0: USB ACM device
[509372.190177] usb-storage 1-2.3:1.2: USB Mass Storage device detected
[509372.190467] scsi host3: usb-storage 1-2.3:1.2
[509373.200470] scsi host3: scsi scan: INQUIRY result too short (5), using 36
[509373.200481] scsi 3:0:0:0: Direct-Access     Adafruit nRF UF2          1.0  PQ: 0 ANSI: 2
[509373.200825] sd 3:0:0:0: Attached scsi generic sg0 type 0
[509373.202317] sd 3:0:0:0: [sdb] 65801 512-byte logical blocks: (33.7 MB/32.1 MiB)
[509373.202556] sd 3:0:0:0: [sdb] Write Protect is off
[509373.202559] sd 3:0:0:0: [sdb] Mode Sense: 03 00 00 00
[509373.202782] sd 3:0:0:0: [sdb] No Caching mode page found
[509373.202784] sd 3:0:0:0: [sdb] Assuming drive cache: write through
[509373.296933]  sdb:
[509373.297002] sd 3:0:0:0: [sdb] Attached SCSI removable disk

Software

Working platformio example project for the nice!nano and supermini/promicro nrf52840 clones: https://github.com/bertrik/nicenano-example

Links:

Getting 'circuitpython' to work:

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