2 layers363.5 × 84 mm
2 layers128.2 × 112.1 mm
Just split
semicontinuity/embedded1Embedded projects
- Size
- 128.2 × 112.1 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 128
- Nets
- 89
- Pads
- 692
- Tracks, vias
- 2,758, 276
- Pours
- 3
- Routed
- Yes
- KiCad
- KiCad 5 (file 20171130)
- Created
- 28 Jun 2012
- Updated
- 8 Sep 2026
Overview
Just split is an open-source printed circuit board by semicontinuity, from the semicontinuity/embedded repository on GitHub. It is a 2-layer board of 128.2 × 112.1 mm with 128 parts on 89 nets, routed with 2,758 tracks and 276 vias.
It is built around the ATMEGA88-20PU, SK6812MINI-E and MMBT3904. Its parts include 39 diodes, 28 resistors, 19 switches, 19 inductors and 5 capacitors. It belongs with the AVR (ATmega, ATtiny) boards of this library.
Main components
3
ATMEGA88-20PU
PDIP-28-40℃~+85℃ 10bit 1KB 2.7V~5.5V 20MHz 23 512Byte 8 Bit 8KB AVR Built-in FLASH PDIP-28 Microcontrollers (MCU/MPU/SOC) ROHSMicrochip TechnologyMicrocontrollers (MCU/MPU/SOC)
SK6812MINI-E
SMD-40℃~+85℃ 0.6mA 1.78mm 120mcd~240mcd 120° 160mcd~320mcd 1kHz 2.8mm 2000V 3.2mm 3.7V~5.5V 460nm~470nm 515nm~525nm 620nm~625nm 800Kbit/s 815mcd~1275mcd Semi-transparent lens SMD RGB LEDs(Built-in IC) ROHSOPSCO OptoelectronicsRGB LEDs(Built-In IC)
MMBT3904
SOT-23-55℃~+150℃ 1 NPN 100 100nA 200mA 200mW 300MHz 300mV 40V 6V NPN SOT-23 Bipolar (BJT) ROHSJiangsu Changjing Electronics Technology (CJ)Bipolar (BJT)
README
README.mdEmbedded projects.
Projects for AVR microcontrollers.
- Primitive alarm
- Primitive terminal
- Voltage relay
- Mood lamp - firmware under development
- Primitive motion sensor controller, that works in pair with primitive alarm
- Servo controller - unfinished, no firmware yet
- LED dimmer, controlled via CAN bus
- CAN bus router - firmware under development
- Roller shutter controller, controlled via CAN bus
- Humidity meter
Parts
128| Qty | Value | Footprint | References |
|---|---|---|---|
| 19 | D | kbd:D3_SMD | D1, D2, D3, D4, D5, D6, D10, D11, D12, D14, D15, D16, D17, D18, D19, D20 +3 |
| 19 | SK6812MINI | kbd:SK6812MINI_rev | L1, L2, L3, L4, L5, L6, L10, L11, L12, L14, L15, L16, L17, L18, L19, L20 +3 |
| 19 | SW_PUSH | kbd:Choc_Hotswap | SW1, SW2, SW3, SW4, SW5, SW6, SW10, SW11, SW12, SW14, SW15, SW16, SW17, SW18, SW19, SW20 +3 |
| 16 | LED_Dual_CAC | LED_THT:LED_Rectangular_W5.0mm_H2.0mm-3Pins | D13, D21, D22, D23, D24, D25, D26, D27, D28, D29, D30, D31, D32, D33, D34, D35 |
| 12 | 330 | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R1, R2, R3, R4, R5, R6, R7, R8, R9, R10, R11, R12 |
| 8 | kbd:Jumper | JP2, JP3, JP4, JP5, JP6, JP7, JP8, JP9 | |
| 5 | 10k | Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P7.62mm_Horizontal | R18, R19, R20, R21, R22 |
| 4 | 0.1 | Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C1, C2, C4, C5 |
| 4 | 10k | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R25, R26, R27, R28 |
| 4 | LED | LED_SMD:LED_0805_2012Metric_Pad1.15x1.40mm_HandSolder | D36, D37, D38, D39 |
| 4 | MMBT3904 | Package_TO_SOT_SMD:SOT-23 | Q1, Q2, Q3, Q4 |
| 4 | R | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R16, R17, R23, R24 |
| 3 | 10k | Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal | R13, R14, R15 |
| 2 | ATmega88-20PU | Package_DIP:DIP-28_W7.62mm | U1, U2 |
| 2 | MJ-4PP-9 | kbd:MJ-4PP-9 | J1, J3 |
| 1 | CP | Connector_Wire:SolderWire-0.5sqmm_1x02_P4.6mm_D0.9mm_OD2.1mm | C3 |
| 1 | OLED | kbd:OLED | J2 |
| 1 | RESET | kbd:ResetSW | RSW2 |
Questions
How big is the Just split PCB?
It measures 128.2 × 112.1 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Just split use?
128 parts, built around the ATMEGA88-20PU, SK6812MINI-E and MMBT3904. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.
Where can I download the Just split KiCad files?
From the semicontinuity/embedded repository on GitHub, at the commit this page was made from: the board is target/just-split/hardware/just-split.kicad_pcb. PCBKit opens the board in the browser, with nothing to install.
Can I use the Just split design in my own project?
Its repository states no licence, so its author keeps all rights: ask semicontinuity before reusing the design.
More from semicontinuity/embedded
12- 2 layers133.8 × 91.2 mm
- 4 layers100 × 100 mm
- 2 layers200 × 200 mm
- 2 layers38 × 52.5 mm
- 2 layers31.2 × 15.2 mm
- 2 layers38.1 × 15.2 mm
- 2 layers35.9 × 15.2 mm
- 2 layers44.5 × 15.2 mm
- 2 layers43.8 × 15.2 mm
- 2 layers46.3 × 15.2 mm
- 2 layers23.7 × 66.4 mm
Similar boards
- 2 layers49.9 × 51.6 mm
- 2 layers37 × 76.5 mm
Temp ref
acamilo/Cheap-Feaver-Screener-PID-Control-PCB
PCB to control two heating elements with i2c or dallas temp sensors.
51 parts1 - 4 layers78 × 50.9 mm
CB-01
ayaxan7/CB-01
NeonCore is a cyberpunk-inspired electronic badge built around the RP2040 microcontroller. The project combines embedded hardware with custom PCB artwork, resulting in a compact development badge that is both functional…
68 parts - 2 layers120 × 102.5 mm
Dsug cctv BOARD
LucasLHenry/spelltwister
This is the third version of the code for the Spelltwister module with CCTV. This version uses the Arduino platform and the RP2040, a chip developed by Raspberry Pi for their RPi Pico board.
251 partsMIT - 4 layers95 × 55.5 mm
EinkPDA keyboard
TalismanDesign/PocketMage_PDA
An E-Ink PDA device using the ESP32 S3.
137 parts2kApache-2.0 - 4 layers99 × 53.3 mm
PSLab
fossasia/pslab-hardware
PSLab Hardware Design and Schematics https://pslab.io
199 parts1.7kApache-2.0 - 2 layers90 × 25.5 mm
- 4 layers85 × 56 mm
