CAN Bus
I got my ELM usb adapter from SECONS in Prague, around 100 years ago.
http://www.obd-2.com/ See also tenrec not 8track, which has been gone for a decade.
2022-12-10 back looking at this, at least a hundred years have elapsed (Linux time) since I started this page.
CAN interfaces
Raspberry Pi
2024-09-25 I unpacked these 2 Waveshare Pi hats today. They both have handy features like jumpers or dip switches to select termination and TVS protection.
Waveshare RS485 CAN HAT (Pi Zero footprint) Includes both MCP2515 and MAX485 transceivers; I don't have a use for RS485 at the moment.
Waveshare 2-channel CAN HAT (full size Pi footprint) Includes 2 MCP2515 transceivers, so you can do loop back testing, handy. Or put one on the instrumentation bus and one on the OBD II port?
Waveshare has a CAN FD board too, but I don't think I need that right now.
Open hardware Pi CAN Board Controller Area Network based on the MCP2515 controller.
WICAN from Meat Pi, based on the ESP32C3, here is their github page. https://github.com/meatpiHQ/wican-fw
Grove
See Grove.
SEEED Studio CAN-BUS module and the ODB II CAN BUS development kit, each about about $20
https://www.seeedstudio.com/blog/2019/11/27/introduction-to-can-bus-and-how-to-use-it-with-arduino/
There is a newer Seeed Studio "Serial CAN FD module", $4.90, I bought two, from Digikey. See https://docs.longan-labs.cc/114992978/ It has its own MCU, it's a GD32E103 which is based on the ARM Cortex M4. (Of course)
Other
https://www.hackster.io/kenliao/vehicle-gui-can-bus-display-05fb45
Sparkfun UBM32 controller: USB 32-Bit Whacker - PIC32MX795 Development Board $40
Software
https://github.com/nopnop2002/esp-idf-CANBus-Monitor There is an ESP32-C3 version too.
Dashboards
"RealDash" looks like it might be fun. It runs on Android, maybe I could use an old phone or tablet. I have enough of those now.
Circuit Cellar article: eDash Robin Brophy Sep 2011 issue 254
Resources
Call it car hacking or CAN hacking https://illmatics.com/carhacking.html
Elm Electronics the folks who make the interface.
OBDtester and pyOBD
OBD Auto Doctor Free and paid versions, including Linux. The paid version is $20 per year.
Python
There are around 700 forks of pyobd... the one that shows up in pypi.org I think appears to be Brendan Whitfield's.
This one looks interesting too though. barracuda-fsh / pyobd