HardLabs

12key

mknudsen404-QA·4KeyPOC·hardware/kicad/12key/12key.kicad_pcb

12key PCB layout, top view — open source ESP32 board by mknudsen404-QA

About the 12key PCB

12key is an open source ESP32 PCB design by mknudsen404-QA, published on GitHub. It is a 2-layer board measuring 87.2 × 108.7 mm, with 58 components from 28 distinct parts.

Its main chip is the ESP32-S3-WROOM-1-N16R8, from the ESP32 family. Other key parts include the XL9555 / PCF8575 (TSSOP-24), AP2112K-3.3 and 74LVC1G17. By type, the board carries 12 switches, 12 diodes, 9 capacitors, 7 resistors, 4 ICs and 2 connectors.

It belongs with the displays & leds and usb & debug tools designs in this gallery.

From the project

Three real KiCad projects for the tiered USB agent-status keypad line described in docs/design/4key-product-line-idea.md, and the V2 custom-PCB direction in SWITCHBOARDDESIGN.md`.

Three real KiCad projects for the tiered USB agent-status keypad line described in docs/design/4key-product-line-idea.md, and the V2 custom-PCB direction in SWITCHBOARDDESIGN.md`.

The 4key board is the drop-in electrical equivalent of the currently shipping firmware/neokey/neokey.ino build: same 4 keys, same 3-agent + 1 push-to-talk split, same USB-serial JSON-lines protocol to host/switchboardbridge.py`. It replaces the purchased Adafruit NeoKey 1x4 (and its Seesaw microcontroller) with one XL9555-class I2C expander and one addressable-LED chain, per the V2 direction.

Main components on the 12key

ESP32-S3-WROOM-1-N16R8XL9555 / PCF8575 (TSSOP-24)AP2112K-3.374LVC1G17

12key bill of materials (BOM)

58 components, 28 distinct parts.

QtyPartRefs
1
ESP32-S3-WROOM-1-N16R8
U1
1
XL9555 / PCF8575 (TSSOP-24)
U2
1
AP2112K-3.3
U3
1
74LVC1G17
U4
1
USB_C_Receptacle
J1
1
SPARE / DEBUG
J2
12
100n
CL1, CL2, CL3, CL4, CL5, CL6, CL7, CL8 +4
1
AGENT1
SW1
1
AGENT2
SW2
1
AGENT3
SW3
1
AGENT4
SW4
1
AGENT5
SW5
1
AGENT6
SW6
1
AGENT7
SW7
1
AGENT8
SW8
1
AGENT9
SW9
1
AGENT10
SW10
1
AGENT11
SW11
1
PTT
SW12
12
SK6812MINI
D1, D2, D3, D4, D5, D6, D7, D8 +4
Show 8 more
QtyPartRefs
3
10u
C1, C3, C9
2
1u
C2, C6
3
100n
C4, C5, C7
1
22u
C8
2
10k
R1, R6
2
5.1k
R2, R3
2
4.7k
R4, R5
1
330
R7

12key design files

The KiCad project lives in the mknudsen404-QA/4KeyPOC repository on GitHub; these links point at the commit this page was built from.

12key: common questions

What microcontroller does the 12key use?

The 12key is built around the ESP32-S3-WROOM-1-N16R8, from the ESP32 family.

How big is the 12key PCB?

The 12key measures 87.2 × 108.7 mm, has 2 copper layers and is 1.6 mm thick.

How many components are on the 12key?

58 components, from 28 distinct parts. The full bill of materials is listed on this page.

Where can I download the 12key design files?

From the mknudsen404-QA/4KeyPOC repository on GitHub, which has the KiCad layout and the schematic; the links under Design files point to each one.

Can I use the 12key design in my own project?

The repository has no license, so all rights stay with mknudsen404-QA. Use it as a reference, and ask the author before reusing the design.

Can I test firmware for the 12key without the hardware?

Yes. HardLabs builds a simulation of the board from its netlist and BOM, so you can run and debug ESP32 firmware against it before you order a PCB.

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