2 layers86 × 67 mm
AR488 ESP32
joseluu/MCP-AR-488-ESP32
The idea is to have AI help me build electronics. AI needs eyes, the eyes are the oscilloscope which is used through an MCP interface.
22 parts2
2 layers37 × 17 mm
OBD2C
dzid26/OBD2C1Unlike harness box, OBD2-C doesn't use the relay.
- Size
- 37 × 17 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 25
- Nets
- 28
- Pads
- 96
- Tracks, vias
- 294, 75
- Pours
- 97
- Routed
- Yes
- KiCad
- KiCad 8.0 (file 20240108)
- Created
- 30 Oct 2024
- Updated
- 7 Mar 2025
Overview
OBD2C is an open-source printed circuit board by dzid26, from the dzid26/OBD2C repository on GitHub. It is a 2-layer board of 37 × 17 mm with 25 parts on 28 nets, routed with 294 tracks and 75 vias.
It is built around the AO3401A, MMBT5551L and SMBJ30CA. Its parts include 7 resistors, 4 diodes, 2 capacitors, 2 transistors and 2 connectors.
Main components
3
AO3401A
SOT-231 P-Channel 14nC@10V 30V 47mΩ@10V、60mΩ@4.5V、85mΩ@2.5V 4A 55pF 645pF 80pF 900mV SOT-23 MOSFETs ROHSAlpha & Omega SemiconductorMOSFETsMMBT5551L
SOT-23-55℃~+150℃ 1 NPN 100nA 160V 250mV 300mW 600mA 6V 80 NPN SOT-23 Bipolar (BJT) ROHSonsemiBipolar (BJT)
SMBJ30CA
SMB(DO-214AA)-55℃~+150℃ 12.4A 1uA 30V 33.3V 48.4V 600W@10/1000us Bidirectional TVS SMB(DO-214AA) ESD and Surge Protection (TVS/ESD) ROHSDOWOESD And Surge Protection (TVS/ESD)
README
README.mdDesigned using Kicad 8
Unlike harness box, OBD2-C doesn't use the relay.
The purpose of it is to sniff CAN buses that are already present in OBD-2 port, similar to what white panda was doing in the past, but compatible with OBD-C, though often only diagnostic CAN is populated on OBD-2.
The device exposes three CAN buses out of OBD-C:
- CAN0 (3, 11)
- CAN1 is routed to the JST (pin 2,3) connector (can be connected .e.g to StepperServoCAN) and has optional 120ohm termination resistor (see jumpers). Alternatively, bus 1 can be rerouted using jumpers as a GMLAN (obd pin 1) as in white panda - but unlike white panda it uses single wire hack and is not tested
- CAN2 (pins 12, 13)
- CAN3 (pins 6, 14) - this one can be used e.g. as "ELM327" or vin reading in openpilot
As seen from PCB side
Some notes regarding openpilot bus names mapping to STM32 peripherals and harness - (the indexes are not always consistent):
HARNESS_STATUS_NORMAL
| openpilot | STM32F4 | Harness | WhitePanda |
|---|---|---|---|
| sbu1 | sbu2 | ||
| sbu2 | sbu1 | ||
| bus 0 | CAN1 | CAN0 | CAN1 |
| bus 1 | CAN2 | CAN1 | CAN2 |
| bus 1(obd) | CAN2 alt | CAN3 | GMLAN |
| bus 2 | CAN3 | CAN2 | CAN3 |
HARNESS_STATUS_FLIPPED
| openpilot | STM32F4 | Harness | WhitePanda |
|---|---|---|---|
| sbu1 | sbu1 | ||
| sbu2 | sbu2 | ||
| bus 0 | CAN3 | CAN0 | CAN1 |
| bus 1 | CAN2 alt | CAN1 | CAN2 |
| bus 1(obd) | CAN2 | CAN3 | GMLAN |
| bus 2 | CAN1 | CAN2 | CAN3 |
+obd means set_obd_multiplexing(True) in openpilot aka panda.set_obd(True) in panda lib aka set_can_mode(CAN_MODE_OBD_CAN2) in panda firmware.
Confusing? Yes. Especially inside panda firmware.
Parts
25| Qty | Value | Footprint | References |
|---|---|---|---|
| 3 | 10K | Resistor_SMD:R_0402_1005Metric | R3, R5, R6 |
| 2 | D_Schottky | Diode_SMD:D_SOD-323 | D1, D2 |
| 1 | 100n | Capacitor_SMD:C_0603_1608Metric | C1 |
| 1 | 11V | Diode_SMD:D_SOD-123 | D4 |
| 1 | 120R | Jumper:SolderJumper-2_P1.3mm_Open_TrianglePad1.0x1.5mm | JP3 |
| 1 | 120R | Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolder | R2 |
| 1 | 12V | Jumper:SolderJumper-2_P1.3mm_Open_TrianglePad1.0x1.5mm | JP4 |
| 1 | 12V disconnect | Jumper:SolderJumper-2_P1.3mm_Bridged_RoundedPad1.0x1.5mm | JP6 |
| 1 | 150 | Resistor_SMD:R_0603_1608Metric | R7 |
| 1 | 1K | Resistor_SMD:R_0603_1608Metric | R4 |
| 1 | 1L | Jumper:SolderJumper-2_P1.3mm_Open_TrianglePad1.0x1.5mm | JP7 |
| 1 | 200R | Resistor_SMD:R_0805_2012Metric | R1 |
| 1 | 470n | Capacitor_SMD:C_0805_2012Metric | C2 |
| 1 | AO3401A | Package_TO_SOT_SMD:SOT-23 | Q2 |
| 1 | Conn_01x04_Socket | CONN-TH_B4B-XH-A-BK-LF-SN | J2 |
| 1 | D2_bypass | Jumper:SolderJumper-2_P1.3mm_Open_RoundedPad1.0x1.5mm | JP5 |
| 1 | GM_gnd | Jumper:SolderJumper-2_P1.3mm_Open_TrianglePad1.0x1.5mm | JP2 |
| 1 | GM_sig | Jumper:SolderJumper-2_P1.3mm_Open_TrianglePad1.0x1.5mm | JP1 |
| 1 | MMBT5551L | Package_TO_SOT_SMD:SOT-23 | Q1 |
| 1 | OBDII | obd2c:OBDII | M1 |
| 1 | SMBJ30CA | Diode_SMD:D_SOD-123F | D3 |
| 1 | USB Type-C | part:USB_C_Receptacle_GCT_USB4115-03-C | J1 |
Questions
How big is the OBD2C PCB?
It measures 37 × 17 mm and has 2 copper layers, 1.6 mm thick.
What parts does the OBD2C use?
25 parts, built around the AO3401A, MMBT5551L and SMBJ30CA. 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 OBD2C KiCad files?
From the dzid26/OBD2C repository on GitHub, at the commit this page was made from: the board is kicad_project/OBD2-C.kicad_pcb and its schematic kicad_project/OBD2-C.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the OBD2C design in my own project?
Its repository states no licence, so its author keeps all rights: ask dzid26 before reusing the design.
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