HardLabs

3leaf left

marcuswu·leaf-fold·PCB/left/3leaf_left.kicad_pcb

3leaf left PCB layout, top view — open source Nordic nRF board by marcuswu

About the 3leaf left PCB

3leaf left is an open source Nordic nRF PCB design by marcuswu, published on GitHub under the MIT license. It is a 2-layer board measuring 146.7 × 75.4 mm, with 62 components from 14 distinct parts.

Its main chip is the HOLYIOT-18010-NRF52840, from the Nordic nRF family. Other key parts include the BQ24075RGT and XC6220B331MR. By type, the board carries 23 switches, 23 diodes, 6 resistors, 5 capacitors, 3 ICs and 2 connectors.

It belongs with the keyboards and iot & wireless designs in this gallery.

From the project

After building my first keyboard, a Lily58, I started following r/ErgoMechKeyboards, r/olkb, and r/MechanicalKeyboards. It was then that I came across the mikefive, a 5mm tall keyboard utilizing Kailh PG1316S keyswitches.

After building my first keyboard, a Lily58, I started following r/ErgoMechKeyboards, r/olkb, and r/MechanicalKeyboards. It was then that I came across the mikefive, a 5mm tall keyboard utilizing Kailh PG1316S keyswitches.

I had always been more interested in low profile keyboards than clacky mechanical keyboards with a lot of key travel, so the mikefive inspired me. I was not ready (and may never be) to reduce down to 5 columns like the mikefive, but I had been intending to learn to design a PCB for some time now.

Main components on the 3leaf left

HOLYIOT-18010-NRF52840BQ24075RGTXC6220B331MR

3leaf left bill of materials (BOM)

62 components, 14 distinct parts.

QtyPartRefs
1
HOLYIOT-18010-NRF52840
U1
1
BQ24075RGT
U3
1
XC6220B331MR
U4
1
5034801600
J1
1
USB_C_Receptacle_USB2.0_16P
J2
22
Keyswitch
S1, S2, S3, S4, S5, S6, S7, S8 +14
1
Switch
SW1
22
Diode
D1, D2, D3, D4, D5, D6, D7, D8 +14
1
1N4148W
D23
5
C
C1, C2, C3, C4, C5
3
10k
R1, R2, R3
1
10m
R4
1
5.1k
R5
1
5.1
R6

3leaf left design files

The KiCad project lives in the marcuswu/leaf-fold repository on GitHub; these links point at the commit this page was built from.

3leaf left: common questions

What microcontroller does the 3leaf left use?

The 3leaf left is built around the HOLYIOT-18010-NRF52840, from the Nordic nRF family.

How big is the 3leaf left PCB?

The 3leaf left measures 146.7 × 75.4 mm, has 2 copper layers and is 0.8 mm thick.

How many components are on the 3leaf left?

62 components, from 14 distinct parts. The full bill of materials is listed on this page.

Where can I download the 3leaf left design files?

From the marcuswu/leaf-fold repository on GitHub, which has the KiCad layout and the schematic; the links under Design files point to each one.

Can I use the 3leaf left design in my own project?

Yes, under the terms of its MIT license, which marcuswu chose for the repository.

Can I test firmware for the 3leaf left without the hardware?

Yes. HardLabs builds a simulation of the board from its netlist and BOM, so you can run and debug Nordic nRF firmware against it before you order a PCB.

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