HardLabs

Mithril

sanfeps·mithril_kb

Mithril PCB layout, top view — open source AVR/Arduino board by sanfeps
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About the Mithril PCB

Mithril is an open source AVR/Arduino PCB design by sanfeps, published on GitHub. It is a 4-layer board measuring 269.8 × 158.8 mm, with 211 components from 23 distinct parts.

Its main chip is the ATMEGA32U4-A, from the AVR/Arduino family. Other key parts include the USB6B1. By type, the board carries 108 diodes, 54 switches, 25 capacitors, 10 resistors, 6 connectors and 4 ICs.

It belongs with the keyboards and displays & leds designs in this gallery.

From the project

mithril keyboard, a split keyboard with 4x6 column ortholinear staggered keys and 3 thumb keys.

A 54-key (27 per side) column-staggered split ergonomic mechanical keyboard with per-key underglow, USB-C on each half, and a dual-MCU design.

- Split — two independent halves connected over TRRS - MCU — ATmega32U4 on each half (true split, dual-MCU) - Layout — 4×5 column-staggered grid + outer pinky column + thumb cluster (27 keys/side) - Switches — MX-compatible, Kailh hotswap sockets (1u plated) - Lighting — SK6812MINI-E reverse-mount per-key underglow - Connectors — USB-C on both halves, TRRS jack for inter-half communication - Case — 3D-printed shell + PCB top plate - Firmware — QMK…

Mithril, from the project README
From the project README

Main components on the Mithril

USB6B1ATMEGA32U4-A

Mithril bill of materials (BOM)

211 components, 23 distinct parts — part numbers from the project's BOM.

QtyPartRefs
2
USB6B1
U1, U3
2
ATMEGA32U4-A
ATmega32U4-A
U2, U4
2
16MHZ
16MHz
Y1, Y2
2
AVR-ISP-6
J1, J4
2
USB_C_RECEPTACLE_USB2.0_16P
USB_C_Receptacle_USB2.0_16P
J2, J5
2
AUDIOJACK4
AudioJack4
J3, J6
54
Keyswitch
S1, S2, S3, S4, S5, S6, S7, S8 +46
54
Diode
D1, D2, D3, D4, D5, D6, D7, D8 +46
54
SK6812MINI-E
D55, D56, D57, D58, D59, D60, D61, D62 +46
2
FerriteBead
FB1, FB2
4
22P
22p
C1, C2, C18, C19
11
100N
100n
C3, C5, C6, C7, C8, C9, C10, C20 +3
2
1u
C4, C21
2
10U
10u
C11, C28
1
10NF
10nF
C15
1
100NF
100nF
C16
1
4.7UF
4.7uF
C17
1
100N
10nF
C23
1
100NF
100n
C24
1
100N
4.7uF
C25
Show 3 more
QtyPartRefs
4
5K1
5k1
R1, R2, R6, R7
2
10K
10k
R3, R8
4
22
R4, R5, R9, R10

Mithril design files

The KiCad project lives in the sanfeps/mithril_kb repository on GitHub; these links point at the commit this page was built from.

Mithril: common questions

What microcontroller does the Mithril use?

The Mithril is built around the ATMEGA32U4-A, from the AVR/Arduino family.

How big is the Mithril PCB?

The Mithril measures 269.8 × 158.8 mm, has 4 copper layers and is 1.6 mm thick.

How many components are on the Mithril?

211 components, from 23 distinct parts, with part numbers taken from the project's own BOM. The full bill of materials is listed on this page.

Where can I download the Mithril design files?

From the sanfeps/mithril_kb repository on GitHub, which has the KiCad layout, the schematic and the BOM; the links under Design files point to each one.

Can I use the Mithril design in my own project?

The repository has no license, so all rights stay with sanfeps. Use it as a reference, and ask the author before reusing the design.

Can I test firmware for the Mithril without the hardware?

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

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