J1850VPW Open Source Module (USB)

[Fixed until broken]

I've been working on a few different J1850VPW modules. I released one recently that is STM32-based and open source. I do sell them, but all the Gerber files and schematics are available if you want to build it yourself.

IMG20260402132014[1].jpg

Hardware: https://github.com/garnerm91/J1850VPW_USB_HW-SW
No obsolete parts and low BOM cost.
Schematics are available
Gerbers are available.
Does not require 12 volts

Firmware: https://github.com/garnerm91/J1850VPW_USB
STM32CUBE IDE
It uses a protocol I use for microcontroller-to-microcontroller comms. If someone wants to make support AT commands, that would be a welcome fork. The current command structure works like this: Frames use STX(0x02)/ETX(0x03) framing: [ 0x02 | LEN | CMD | data... | 0x03 ] LEN includes the CMD byte. The device will respond with an ACK = 0x06 or NACK = 0x15.
Commands are
0x01 RX Mode 0x01 = enable, 0x00 = disable
0x02 Send frame J1850 bytes (CRC appended automatically)

Software: Same link as HW
The program for it, "Bridge PRO," does a few things.
-It was written to configure my 99-02 swap box module.
-It also allows for data logging of the J1850VPW bus.
-It also supports scripted playbacks. The scripts are just .txt files and follow like this

Code: Select all

// This is a comment
*100
28 FF 40 06 07 0F 0F
28 93 40 01 FF FF
#this is another type of comment, and then a 500ms delay
*500
49 92 40 42
88 3B 1A 05 00

So # or// is a comment, and * tells it to change the delay between frames. You don't include the CRC, it will figure that out on its own.

Video: https://youtu.be/8Q_QOkDVAA0?si=wB11cUSgiiLlm0_x

Full disclosure, I did use AI as a time-saving tool. Software usage was heavier than firmware usage. Mostly because the software part was mostly just for me, but I figured I would share it so people at least have a starting point.

[antus]

That looks great, well done! Do you have any plans to support any other protocols on the PC side?

[Fixed until broken]

Do you have any plans to support any other protocols on the PC side?

On the "Bridge Pro" side of things, not really, it was really just an app for me to use as part of the test procedure for my 99-02 swap box I sell. If at some point the module gets Attention Command Set like ELM327s, I will put some effort into making sure it works with IPChammer, which should work with PCMhammer. If not, I might write my weird protocol for IPChammer. The app is really an afterthought.

[pman92]

This is awesome, well done.
Also just found another great Youtube channel to subscribe to

[Fixed until broken]

Thank you. Always great to get a new subscriber.

I've got some ideas for future versions of the hardware. I am probably going to add a header to allow you to skip using the USB port and go direct to microcontroller via uart if want to tie this into an embedded project.