2 layers82.5 × 93 mm
4 layers120 × 120 mm
ATmega328P Dev Board
- Size
- 120 × 120 mm
- Copper layers
- 4
- Thickness
- 1.6 mm
- Parts
- 37
- Nets
- 61
- Pads
- 176
- Tracks, vias
- 317, 9
- Routed
- Yes
- KiCad
- KiCad 9.0 (file 20241229)
- Created
- 1 Mar 2026
- Updated
- 1 Mar 2026
Overview
SEM4 is an open-source printed circuit board by AdityaSamani, from the AdityaSamani/PCB-Project repository on GitHub. It is a 4-layer board of 120 × 120 mm with 37 parts on 61 nets, routed with 317 tracks and 9 vias.
It is built around the ATMEGA328-PU, AMS1117-3.3 and L7805, with the ULN2803A among its other parts. Its parts include 10 capacitors, 10 connectors, 5 ICs, 4 resistors and 2 diodes. It belongs with the AVR (ATmega, ATtiny) boards of this library.
Main components
4
ATMEGA328-PU
PDIP-28-40℃~+85℃ 1.8V~5.5V 10bit 1KB 20MHz 23 2KB 32KB 8 Bit AVR Built-in FLASH PDIP-28 Microcontrollers (MCU/MPU/SOC) ROHSMicrochip TechnologyMicrocontrollers (MCU/MPU/SOC)
AMS1117-3.3
SOT-223-40℃~+125℃ 0.003%Vout 1 1.1V@(800mA) 15V 1A 3.3V 5mA 72dB@(120Hz) Fixed Over Current Protection、Short Circuit Protection、Thermal shutdown Positive SOT-223 Voltage Regulators - Linear, Low Drop Out (LDO) Regulators ROHSAdvanced Monolithic SystemsVoltage Regulators - Linear, Low Drop Out (LDO) Regulators
L7805
TO-220ST0℃~+125℃@(Tj) 1 1.2A 20V 2V@(1A) 42uV 500uA 5V 73dB@(120Hz) Fixed Positive Short Circuit Protection TO-220ST Voltage Regulators - Linear, Low Drop Out (LDO) Regulators ROHSOSENVoltage Regulators - Linear, Low Drop Out (LDO) Regulators
ULN2803A
SOP-18-300mil-40℃~+85℃ 0.93mA 100uA 15pF 20uA 30V 500mA 50V 8 SOP-18-300mil Darlington Transistor Arrays ROHSUMWDarlington Transistor Arrays
README
README.mdPCB-Project
ATmega328P Dev Board
Parts
37| Qty | Value | Footprint | References |
|---|---|---|---|
| 4 | R | Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P7.62mm_Horizontal | R1, R2, R3, R4 |
| 3 | 1uf | Capacitor_THT:C_Disc_D3.0mm_W1.6mm_P2.50mm | C7, C8, C10 |
| 3 | Conn_01x08 | Connector_JST:JST_EH_B8B-EH-A_1x08_P2.50mm_Vertical | J1, J6, J7 |
| 2 | 100nf | Capacitor_THT:C_Disc_D3.0mm_W1.6mm_P2.50mm | C4, C5 |
| 2 | 22pf | Capacitor_THT:C_Disc_D3.0mm_W1.6mm_P2.50mm | C2, C3 |
| 2 | Barrel_Jack | Connector_BarrelJack:BarrelJack_Wuerth_6941xx301002 | J3, J4 |
| 2 | LED | LED_THT:LED_D2.0mm_W4.0mm_H2.8mm_FlatTop | D1, D2 |
| 2 | SW_MEC_5G | Button_Switch_SMD:SW_MEC_5GSH9 | SW1, SW2 |
| 2 | Screw_Terminal_01x02 | TerminalBlock:TerminalBlock_MaiXu_MX126-5.0-02P_1x02_P5.00mm | J9, J10 |
| 1 | 100uf | Capacitor_THT:C_Disc_D3.0mm_W1.6mm_P2.50mm | C9 |
| 1 | 10uf | Capacitor_THT:C_Disc_D3.0mm_W1.6mm_P2.50mm | C6 |
| 1 | 2N7000 | Package_TO_SOT_THT:TO-92_Inline | Q1 |
| 1 | AMS1117-3.3 | Package_TO_SOT_SMD:SOT-223-3_TabPin2 | U3 |
| 1 | ATmega328-P | Package_DIP:DIP-28_W7.62mm | U1 |
| 1 | Buzzer | Buzzer_Beeper:Buzzer_12x9.5RM7.6 | BZ1 |
| 1 | C | Capacitor_THT:C_Disc_D3.0mm_W1.6mm_P2.50mm | C1 |
| 1 | Conn_01x06 | Connector_Hirose:Hirose_DF57H-6P-1.2V_1x06_P1.2mm_Socket | J2 |
| 1 | Conn_02x03_Odd_Even | Connector:Tag-Connect_TC2030-IDC-NL_2x03_P1.27mm_Vertical | J5 |
| 1 | Crystal | Crystal:Crystal_AT310_D3.0mm_L10.0mm_Horizontal | Y1 |
| 1 | FerriteBead | Inductor_THT:L_Radial_D6.0mm_P4.00mm | FB1 |
| 1 | L293 | Package_DIP:DIP-16_W7.62mm | U4 |
| 1 | L7805 | Package_TO_SOT_THT:TO-220-3_Horizontal_TabDown | U2 |
| 1 | Screw_Terminal_01x06 | TerminalBlock:TerminalBlock_MaiXu_MX126-5.0-06P_1x06_P5.00mm | J8 |
| 1 | ULN2803A | Package_DIP:DIP-18_W7.62mm | U5 |
Questions
How big is the SEM4 PCB?
It measures 120 × 120 mm and has 4 copper layers, 1.6 mm thick.
What parts does the SEM4 use?
37 parts, built around the ATMEGA328-PU, AMS1117-3.3, L7805 and ULN2803A. 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 SEM4 KiCad files?
From the AdityaSamani/PCB-Project repository on GitHub, at the commit this page was made from: the board is atmega dev/SEM4.kicad_pcb and its schematic atmega dev/SEM4.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the SEM4 design in my own project?
Its repository states no licence, so its author keeps all rights: ask AdityaSamani before reusing the design.
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