2 layers133.4 × 127 mm
Mss xcade
IowaScaledEngineering/mss-xcade
Modular Signal System 4 Port Complex Cascade
233 partsGPL-3.0
2 layers101.6 × 73.7 mm
I2c headunit
IowaScaledEngineering/i2c-headunit- Size
- 101.6 × 73.7 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 35
- Nets
- 45
- Pads
- 141
- Tracks, vias
- 218, 65
- Pours
- 4
- Routed
- Yes
- KiCad
- KiCad 9.0 (file 20241229)
- Created
- 12 May 2025
- Updated
- 19 Jun 2026
Overview
I2c headunit is an open-source printed circuit board by IowaScaledEngineering, from the IowaScaledEngineering/i2c-headunit repository on GitHub. It is a 2-layer board of 101.6 × 73.7 mm with 35 parts on 45 nets, routed with 218 tracks and 65 vias.
It is built around the ATTINY88-AU, FSM4JSMATR and SM04B-SRSS-TB, with the BSS138K among its other parts. Its parts include 10 capacitors, 7 resistors, 4 connectors, 4 switches and 1 IC. It belongs with the AVR (ATmega, ATtiny) boards of this library.
Main components
4
ATTINY88-AU
TQFP-32(7x7)-40℃~+85℃ 1.8V~5.5V 10bit 12MHz 28 512Byte 64Byte 8 Bit 8KB AVR Built-in FLASH TQFP-32(7x7) Microcontrollers (MCU/MPU/SOC) ROHSMicrochip TechnologyMicrocontrollers (MCU/MPU/SOC)
FSM4JSMATR
SMD-4P,6x6mm-40℃~+85℃ 1.6N 100,000 cycles 24V 50mA 5mm 6mm 6mm Gull Wing Round Button SPST-NO Surface Mount,Vertical Without Bracket SMD-4P,6x6mm Tactile Switches ROHSTE ConnectivityTactile Switches
SM04B-SRSS-TB
Header SR 1.0 SMT side entry, 1mm pitchJSTUncategorised
BSS138K
SOT-231 N-channel 1.5Ω@10V 1V 2.2pF 25pF 400mA 417mW 60V 650pC@4.5V 9.7pF N-Channel SOT-23 MOSFETs ROHSElecSuperMOSFETs
Parts
35| Qty | Value | Footprint | References |
|---|---|---|---|
| 7 | 0.1uF | Capacitor_SMD:C_0805_2012Metric | C3, C4, C5, C6, C7, C8, C9 |
| 4 | 1k | Resistor_SMD:R_0805_2012Metric | R2, R3, R4, R5 |
| 4 | 3-1825910-1 | ISE_UltraLibrarian:SW4_1825910-H_TEC | SW1, SW2, SW3, SW4 |
| 4 | MountingHole | MountingHole:MountingHole_3.2mm_M3_Pad | H1, H2, H3, H4 |
| 2 | SM04B-SRSS | Connector_JST:JST_SH_SM04B-SRSS-TB_1x04-1MP_P1.00mm_Horizontal | J1, J4 |
| 2 | SolderJumper_2_Open | Jumper:SolderJumper-2_P1.3mm_Open_RoundedPad1.0x1.5mm | JP1, JP2 |
| 1 | 10k | Resistor_SMD:R_0805_2012Metric | R6 |
| 1 | 10k | Potentiometer_SMD:Potentiometer_Bourns_TC33X_Vertical | R7 |
| 1 | 10uF | Capacitor_SMD:C_0805_2012Metric | C2 |
| 1 | 1uF | Capacitor_SMD:C_0805_2012Metric | C10 |
| 1 | 330 | Resistor_SMD:R_0805_2012Metric | R1 |
| 1 | 68uF | Capacitor_SMD:CP_Elec_6.3x5.8 | C1 |
| 1 | ATtiny88-A | Package_QFP:TQFP-32_7x7mm_P0.8mm | U1 |
| 1 | AVR-ISP | Connector:Tag-Connect_TC2030-IDC-NL_2x03_P1.27mm_Vertical | J2 |
| 1 | BSS138K | Package_TO_SOT_SMD:SOT-23 | Q1 |
| 1 | Conn_01x16 | Connector_PinHeader_2.54mm:PinHeader_1x16_P2.54mm_Vertical | JLCD1 |
| 1 | GREEN LED | LED_SMD:LED_0805_2012Metric | D1 |
| 1 | Screw_Terminal_01x08 | TerminalBlock_TE-Connectivity:TerminalBlock_TE_282834-8_1x08_P2.54mm_Horizontal | J3 |
Questions
How big is the I2c headunit PCB?
It measures 101.6 × 73.7 mm and has 2 copper layers, 1.6 mm thick.
What parts does the I2c headunit use?
35 parts, built around the ATTINY88-AU, FSM4JSMATR, SM04B-SRSS-TB and BSS138K. 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 I2c headunit KiCad files?
From the IowaScaledEngineering/i2c-headunit repository on GitHub, at the commit this page was made from: the board is kicad/i2c-headunit/i2c-headunit.kicad_pcb and its schematic kicad/i2c-headunit/i2c-headunit.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the I2c headunit design in my own project?
Its repository states no licence, so its author keeps all rights: ask IowaScaledEngineering before reusing the design.
Similar boards
- 2 layers139.7 × 88.9 mm
- 2 layers114.3 × 188 mm
- 2 layers127 × 76.2 mm
- 2 layers68.6 × 53.3 mm
- 2 layers101.6 × 120.7 mm
Mss cascade basic testjig
IowaScaledEngineering/mss-cascade
Integrated Cascade Module for Free-mo Modular Signal System
101 parts - 2 layers100 × 71.8 mm
- 2 layers50.8 × 76.2 mm
Breadboard-1
bicknell/DCC-Mobile-Decoder
DCC Mobile Decoder Reference Implementation Hardware & Software
76 parts14