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Releases

joric edited this page Oct 14, 2024 · 118 revisions

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. Recommended!

nRFMicro 1.4

1.4 is the newest 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 control, so less code needed (for that go for nRFMicro-1.3, but it doesn't have charging LED).

Schematic and gerbers are in the releases section. I recommend using ZMK on this board (or Circuitpython, it's fun!)

PCBs

Experimental branches

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).

Album with experimental branches: https://imgur.com/a/9GKIXj0

Bill of materials

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.

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.

Soldering

Read the separate Soldering article about assembly, testing and unshielding the module.

image

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.

Pictures

front back

Assembled board

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).

Aq4ipJs

See Components#led-polarity about LED polarity.

References

nRFMicro 1.3

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.

PCBs

Bill of materials

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).

Soldering

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.

nrfmicro-1 3

Pictures

front back

Assembled board

nRFMicro 1.3 view

Control pins

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.

Archive

Older revisions moved to Archive.

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