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Twentypad

HarryCutts·twentypad

Twentypad PCB layout, top view — open source AVR/Arduino board by HarryCutts

About the Twentypad PCB

Twentypad is an open source AVR/Arduino PCB design by HarryCutts, published on GitHub. It is a 2-layer board measuring 79 × 122.4 mm, with 44 components from 14 distinct parts.

Its main chip is the ATMEGA32U4-A, from the AVR/Arduino family. By type, the board carries 20 switches, 9 capacitors, 7 resistors, 3 connectors, 2 diodes and 1 IC.

It belongs with the keyboards designs in this gallery.

From the project

A simple twenty-key macro pad based on the ATMEGA32

This repository contains the KiCAD project for PCB manufacture and assembly. The case was [designed in Onshape][onshape-proj].

[onshape-proj]: https://cad.onshape.com/documents/e1701c21a3cb18f7b5686e27/w/70a0bcde95206762f85e44bf/e/dfee6d06467dfd7de2e80397

Twentypad, from the project README
From the project README

Main components on the Twentypad

ATMEGA32U4-A

Twentypad bill of materials (BOM)

44 components, 14 distinct parts — part numbers from the project's BOM.

QtyPartRefs
1
ATMEGA32U4-A
ATmega32U4-A
U1
1
C13738
16 MHz
Y1
1
USB_C_RECEPTACLE_USB2.0_14P
USB_C_Receptacle_USB2.0_14P
J1
1
AVR-ISP-6
J2
1
CONN_01X05_PIN
Conn_01x05_Pin
J3
20
CherryMX
SW0,0, SW0,1, SW0,2, SW0,3, SW0,4, SW1,0, SW1,1, SW1,2 +12
1
SW_Push
SWR1
2
LED
D1, D2
2
1UF
1uF
C1, C2
5
0.1UF
0.1uF
C3, C4, C5, C6, C9
2
10PF
10pF
C7, C8
2
22
R1, R2
2
5K1
R3, R4
3
1K
R5, R6, R7

Twentypad design files

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

Twentypad: common questions

What microcontroller does the Twentypad use?

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

How big is the Twentypad PCB?

The Twentypad measures 79 × 122.4 mm, has 2 copper layers and is 1.6 mm thick.

How many components are on the Twentypad?

44 components, from 14 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 Twentypad design files?

From the HarryCutts/twentypad 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 Twentypad design in my own project?

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

Can I test firmware for the Twentypad 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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