LK7D

lambdakb·keyboard-lk7d·pcb/lk7d-pcb.kicad_pcb

About the LK7D PCB

LK7D is an open source RP2040/RP2350 PCB design by lambdakb, published on GitHub under the CERN-OHL-S-2.0 license. It is a 2-layer board measuring 57.2 × 57.2 mm, with 29 components from 9 distinct parts.

Its main chip is the XIAO-RP2040, from the RP2040/RP2350 family. Other key parts include the SN74LV1T125DBV. By type, the board carries 8 switches, 8 diodes, 6 LEDs, 3 capacitors, 2 ICs and 2 connectors.

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

From the project

LK7D 7 Keys RGB Macropad

The LambdaKB LK7D is a simple 7 keys hotswap macropad with per-key RGB LEDs and an OLED display. The goal was to create a simple macropad based on the XIAO RP2040 microcontroller that had all the bells and whispers of a modern keyboard.

This was created as an experiment to learn more about designing PCBs and to have a simple and cheap way to test new features (such as integrating OLED displays and RGB LEDs in QMK / Vial).

LK7D, from the project README — From the project README

Main components on the LK7D

XIAO-RP2040 SN74LV1T125DBV

LK7D bill of materials (BOM)

29 components, 9 distinct parts — part numbers from the project's BOM.

Qty	Part	Footprint	Refs
1	XIAO-RP2040	MCU_XIAO_RP2040	U1
1	SN74LV1T125DBV	SOT-23-5	U2
2	PINHD_1x4_Male	PinHeader_1x04_P2.54mm_Vertical	J1, J2
2	RotaryEncoder_Switch_MP	ROT_EC11_THT_sqSilk	SW1, SW2
6	SW_Push	SW_MX_HotSwap_sqSilk	SW3, SW4, SW5, SW6, SW7, SW8
6	SK6812MINI-E	LED_SK6812MINI-E	LED1, LED2, LED3, LED4, LED5, LED6
8	1N4148	Diode_SMD_SOD-123_inSilk	D1, D2, D3, D4, D5, D6, D7, D8
2	100NF 100nF	Capacitor_SMD_1206_inSilk	C1, C2
1	100nF	Capacitor_SMD_1206_inSilk	C3

LK7D design files

The KiCad project lives in the lambdakb/keyboard-lk7d repository on GitHub; these links point at the commit this page was built from.

Layoutpcb/lk7d-pcb.kicad_pcb
Schematicpcb/lk7d-pcb.kicad_sch
BOMoutput/pcb/fabrication/jlcpcb/lk7d-pcb_bom_jlcpcb.csv

LK7D: common questions

What microcontroller does the LK7D use?

The LK7D is built around the XIAO-RP2040, from the RP2040/RP2350 family.

How big is the LK7D PCB?

The LK7D measures 57.2 × 57.2 mm, has 2 copper layers and is 1.6 mm thick.

How many components are on the LK7D?

29 components, from 9 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 LK7D design files?

From the lambdakb/keyboard-lk7d 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 LK7D design in my own project?

Yes, under the terms of its CERN-OHL-S-2.0 license, which lambdakb chose for the repository.

Can I test firmware for the LK7D without the hardware?

Yes. HardLabs builds a simulation of the board from its netlist and BOM, so you can run and debug RP2040/RP2350 firmware against it before you order a PCB.