Join GitHub today
GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together.Sign up
- Built in KiCad and fully autorouted with Freerouting (shouldn't be a problem to modify)
- Same size as Pro Micro (18x33mm), has both MicroUSB and Type-C, Li-Po charger and BT 5.0
- Runs full-featured QMK software (nrf52 fork), uses USB Mass Storage for firmware updates
- Supports wired split keyboards via USB-C, MicroUSB and I2C/Serial TRRS extension cables
- Supports fully wireless split keyboards over Bluetooth, does not need dedicated receivers
Bill of materials
The board schematic is available in the Releases section.
I'd really recommend Vanxy Aliexpress store instead of LCSC. Most components cost about $1, and for extra $1.47 they ship all in a single package with a trackable Aliexpress Standard Shipping.
|U1||C331405||1||SMD||2G4M08S1C||E73 nRF52840||$5-$7 / 1|
|J2||C165948||1||SMD||MC-372||USB-C 16-pin||$0.19 / 1|
|R2,R3||C14675||2||0603||100K||SMD Resistor||$0.61 / 100|
|R8||C98220||1||0603||10K||SMD Resistor||$0.61 / 100|
|R4,R5||C105580||2||0603||5.1K||SMD Resistor||$0.61 / 100|
|R1||C99782||1||0603||4.7K||SMD Resistor||$0.61 / 100|
|R6,R7||C22548||2||0603||1K||SMD Resistor||$0.61 / 100|
|D3||C84263||1||0603||Red||SMD LED||$0.87 / 100|
|D2||C84266||1||0603||Blue||SMD LED||$0.87 / 100|
|C1-C3||C1691||3||0603||10uF||SMD Capacitor||$1.69 / 100|
|Q1||C351408||1||SOT-23-3||AO3407||P-MOSFET||$0.95 / 50|
|D1||C82544||1||SOD-123||1N5819||Schottky Diode||$0.84 / 100|
|U3||C51118||1||SOT-23-5||AP2112K-3.3||VCC Regulator||$0.81 / 10|
|U4||C14879||1||SOT-23-5||MCP73831||Li-Po Charger||$1.02 / 10|
|Y1||C13712||1||TH 2*6mm||32.768KHz||Crystal (opt.)||$0.87 / 10|
|J1||C40943||1||5P||5P 4 legs||MicroUSB (opt.)||$0.46 / 10|
|SW1||C16168||1||SMD||MSK-12C02||SPDT Switch||$1.31 / 10|
- The 4.7K resistor (Li-Po current) can be replaced with 5.1K if you want to save money
- Blue LED comes with Red LED (5 colors 20 pcs each, you also get other colors)
- The 32.768 kHz external crystal is optional (QMK firmware does not use it)
- MicroUSB is an option to replace USB-C (you can solder either of those)
- Bluepill - STM32F103C8T6 ARM STM32 Minimum System Development Board ($1.77)
- CP2102-based Micro USB to UART TTL Module ($0.98)
PCBS.io gerbers are now published on PCBS.io, so you don't even need to download anything. Takes about 9 days for the fabrication (black mask), ships with international USPS tracking number and costs $3.77 total, might be the best PCB manufacturer yet (for the small boards).
- https://pcbs.io/share/rEVPb - $3.77 for 4x with shipping (no edge cuts, no slots, but works)
- https://oshpark.com - $4.70 for 3x with shipping (shipping is longer, takes a month)
PCBS.io plot options (ONLY if you need to modify and reexport the board!)
Manually replace all oval pads with 4-5 round pads (PCBS.io needs round holes on the drill layer), and use the following plot settings:
- disable "Edge.Cuts" layer, enable "Margin" layer (make sure it matches Edge.Cuts)
- enable "Exclude PCB Edge layer from other layers", "Use Protel filename extensions"
- (drill file) enable "PTH and NPTH in a single file"
Assembly guide (nRFMicro 0.03)
I pre-tin underside pads because boards are usually too oxidized to do that just with flux without rubbing the pads. The layer of solder should be as thin as possible to level the module without the gaps. No hot air gun is intended you simply heat them from the other side and pour more solder to the underside pin via those underside pin holes, if needed.
Li-Po battery uses RAW and GND pins (check for 4.2V charging voltage after assembly).
Avoid reverse polarity! If controller appears dead, replace 1N5819 or MCP73831, they fry first.
Testing firmware for nRFMicro 0.03 (upload this file with USB bootloader):
Connect any LED+ to VCC pin and test all the pins consequently via 1K resistor. LED should blink on all GPIO pins. If it doesn't blink, it's mostly bad soldering on the underside pins (maybe you forgot to pre-tin them), add more solder to the pads on the other side and heat them well to fill the gaps.
Red LED should blink if battery is not connected or the power switch is off, it's normal (it's wired directly to the charger).
Elecrow provides pick and place PCB assembly services for mass production. I haven't tried it yet, but it could be fun. See the example here (fully prepped Elecrow pcba spec in the repo):
|SMDs from Vanxy||10||$11.38||2019-04-23||2019-04-27||2019-05-06||13|
|PCBS.io PCBs 0.03||4||$3.77||2019-04-23||2019-05-02||2019-05-14||21|