Releases
This article is about the latest working revisions of nRFMicro. For the older revisions see Archive. Note nRFMicro 1.4 is backward compatible with nRFMicro 1.3 firmware (1.3 needs charger pin pulled down to enable charging), so just use 1.3 firmware for 1.4.
See Pinout article for the board pinout and free (unassigned) pins (there are about 30 general purpose pins that you can use).
Latest 1.4.x is the main branch (adds nRF52833 jumper for pin 1.04), iBOM is 1.4 compatible.
- 1.4.x gerbers: https://github.com/joric/nrfmicro/releases/latest/download/nrfmicro-main-gerbers.zip
- 1.4.x iBOM: https://htmlpreview.github.io/?https://github.com/joric/nrfmicro/blob/main/hardware/ibom/ibom.html
1.4 is a very new board, made in collaboration with Ariamelon. It is compatible with 1.3 firmware, but also has Crystal, full USB/SWD pinout and other improvements: charger and power pins pulled down to avoid floating, added charging LED and removed software charging current control, so less code needed (for that you may build nRFMicro-1.3, it's a bit cheaper).
Schematic and gerbers are in the releases section. I recommend using ZMK on this board (or Circuitpython, it's fun!)
- https://jlcpcb.com (30 boards will cost you about $5 + $7 for shipping). Gerbers: nrfmicro-1.4-gerbers.zip
- https://oshpark.com/shared_projects/nhKgl5ud ($4.70 for 3 pcs with shipping, they also make 0.8 mm PCBs)
- https://www.pcbway.com/project/shareproject/nRFMicro_1_4.html ($5 + $9 shipping - $5 new user coupon for 10 pcs)
- https://www.allpcb.com/sns/bbssubject/ActiveDetail?Id=26313 (ALLPCB project)
Aliexpress Saver shipping is combined with the Standard shipping now, so use Saver where possible to get everyhing at once. Most of the stuff is from the same shop (Vanxy) so you don't really have to pay extra for shipping.
- There's currently a shortage of 2G4M08S1C modules, see Components#alternative-modules.
| Name | LCSC PN | Qty | Package | Value | Description | Aliexpress |
|---|---|---|---|---|---|---|
| U1 | C356849 | 1 | SMD | 2G4M08S1C | E73 nRF52840 | $3-$5 / 1 |
| J1 | C168688 | 1 | SMD | 1.6mm | 16-pin Mid-mount USB-C | $1.17 / 10 |
| R1 | C14675 | 1 | 0603 | 100K | SMD Resistor | $0.61 / 100 |
| R2,R3 | C105580 | 2 | 0603 | 5.1K | SMD Resistor | $0.61 / 100 |
| R4,R8 | C22548 | 2 | 0603 | 1K | SMD Resistor | $0.61 / 100 |
| R5 | C98220 | 1 | 0603 | 10K | SMD Resistor | $0.61 / 100 |
| R6 | C23252 | 1 | 0603 | 820K | SMD Resistor | $0.61 / 100 |
| R7,R9 | C177282 | 2 | 0603 | 2M | SMD Resistor | $0.61 / 100 |
| D1 | C489147 | 1 | SOD-323 | 1N5819 | Schottky Diode | $0.84 / 100 |
| D2 | C84266 | 1 | 0603 | Blue LED | SMD LED | $0.87 / 100 |
| D3 | C84263 | 1 | 0603 | Red LED | SMD LED | $0.87 / 100 |
| Q1,Q2 | C351408 | 2 | SOT-23-3 | AO3407 | P-MOSFET | $0.95 / 50 |
| U2 | C51118 | 1 | SOT-23-5 | AP2112K-3.3 | VCC Regulator | $0.81 / 10 |
| U3 | C32574 | 1 | SOT-23-5 | TP4054 | Li-Po Charger | $0.60 / 20 |
| X1 | C93230 | 1 | 1610 | 32.768 kHz | Crystal (optional *) | $3.37 / 10 |
- nRF5x doesn't really need a crystal (it only saves about 8-10 µA), the default ZMK configuration (1.3) doesn't use it.
- Note the 0.8 mm PCB option (requires 0.8 mm USB-C) makes the board 0.25 mm thinner but super-fragile.
- This BOM was made backward compatible so you could reuse old components. You can improve the board with more expensive substitute components from the Components article. E.g. XC6220 gives you just 8 uA quescent current instead of 55 uA as with AP2112. Also there are better diodes, e.g. BAT60B is 3A instead of 350 mA as 1N5819.
There are also slightly tested experimental branches. USB-C PCB edge connector (needs 0.8 mm PCBs). If you break the middle leaf off it also allows to solder mid-mount USB-C. The switch is 12C02, top-mount USB-C is TYPE-C-31-M-12). The switch adds 1.4 mm, the top-mount USB-C adds 3.2 mm to the PCB (stock 1.4 is 3.2 mm overall, regular Pro Micro is 3.75 mm).
- https://github.com/joric/nrfmicro/tree/devel-1.4-pcb-connector (PCB connector, no switch, ~3.2 mm, tested)
- https://github.com/joric/nrfmicro/tree/devel-1.4-switch-bottom (PCB connector, switch at the bottom, ~4.6 mm, tested)
- https://github.com/joric/nrfmicro/tree/devel-1.4-switch-middle (PCB connector, switch at the middle, ~4.6 mm, tested)
- https://github.com/joric/nrfmicro/tree/devel-1.4-topmount (top-mount USB-C, top switch, tested VERY TALL ~6.2mm)
Album with experimental branches: https://imgur.com/a/9GKIXj0
This board does not need a hot air station, and can be done entirely with a soldering iron. Inner module pads are through-hole, so you can solder from the other side. Read the Soldering article about assembly, testing and unshielding the module.
| front | back |
|---|---|
 |
 |
PCB below is 0.8 mm (needs 0.8 mm USB-C connector) so antenna sits flush with USB-C (1.6 mm PCB version is 0.25 mm taller).
LED polarity: align square bracket on the PCB and green paint on the front of the LED.
The negative electrode of the LED is marked by the green color on the front. The negative electrode of the PCB pad is marked by a silk screen 匚 frame. it's the standard SMD LED footprint, nobody redraws that from scratch (see #17, #39). You do not really need to look at the diode back, ever.
- https://likipiki.gitlab.io/posts/nrfbuild/ Гайд по сборке NRFMicro 1.4 (russian)
Schematic and gerbers are in the releases section.
1.3 revision is pretty good. Short and clean traces, 0.2 mm spacing everywhere, very few components, very cheap. No more problematic high voltage mode as in Archive#nRFMicro-1.2. Power pin (P1.09) and charger pin (P0.05) float and must be properly initialized (e.g. set to zero). Charger control can switch between zero (CR2032), high (Li-Po) or low (LIR2032) modes.
- https://jlcpcb.com (30 boards for about $5 + $7 for shipping). Gerbers: nrfmicro-1.3-gerbers.zip.
- https://www.pcbway.com/project/shareproject/nRFMicro_1_3.html ($5 + $5 coupon for 10 pcs)
| Name | LCSC PN | Qty | Package | Value | Description | Aliexpress |
|---|---|---|---|---|---|---|
| U1 | C356849 | 1 | SMD | 2G4M08S1C | E73 nRF52840 | $3-$5 / 1 |
| J2 | C168688 | 1 | SMD | 1.6mm | 16-pin Mid-mount USB-C | $1.17 / 10 |
| R1 | C14675 | 1 | 0603 | 100K | SMD Resistor | $0.61 / 100 |
| R2,R3 | C105580 | 2 | 0603 | 5.1K | SMD Resistor | $0.61 / 100 |
| R4 | C22548 | 1 | 0603 | 1K | SMD Resistor | $0.61 / 100 |
| R5 | C98220 | 1 | 0603 | 10K | SMD Resistor | $0.61 / 100 |
| R6 | C23252 | 1 | 0603 | 820K | SMD Resistor | $0.61 / 100 |
| R7 | C177282 | 1 | 0603 | 2M | SMD Resistor | $0.61 / 100 |
| D1 | C489147 | 1 | SOD-323 | 1N5819 | Schottky Diode | $0.84 / 100 |
| D2 | C84266 | 1 | 0603 | Blue LED | SMD LED | $0.87 / 100 |
| Q1,Q2 | C351408 | 2 | SOT-23-3 | AO3407 | P-MOSFET | $0.95 / 50 |
| U3 | C51118 | 1 | SOT-23-5 | AP2112K-3.3 | VCC Regulator | $0.81 / 10 |
| U4 | C32574 | 1 | SOT-23-5 | TP-4054 | Li-Po Charger | $0.78 / 10 |
- 100K in the power selector may be replaced with 820K or 2M, also see the Components article for other substitutes.
- 10K resistor (100 mA charging current) can be replaced to 2K for 500 mA (~67 mA in low current mode).
This board does not need a hot air station, and can be done entirely with a soldering iron. Inner module pads are through-hole, so you can solder from the other side. See the Soldering article.
| front | back |
|---|---|
 |
 |
Note that with 1.3 you absolutely HAVE to init POWER_PIN (EXT_VCC pin) explicitly because there's no pull-down and it just floats if uninitialized. Same with the PROG_PIN that controls the charger. Init and set both pins properly. See ZMK section for details.
Older revisions moved to Archive.