Building the ELM329 CAN Device - Part III

So After the first build had failed I determined that the problem was with the CP2102 USB Chip. If I looked closely I could see a solder bridge under one side. It'll take some time to fix it (if it's even possible at this time), so instead I decided to kick off another batch of boards as practice.

As I mentioned earlier I have 3 different revisions of the boards, the red 1.1, a purple 1.2 and purple 1.3. I figured I would try to make one of each for a comparison - between them the layout has a few slight changes and a few component differences. After going through the usual process of the stencil, paste, placement etc I baked all 3 PCBs at the same time.

After a nice baking session

I'm not sure if you can tell, but the center IC on the Red board (almost looks orange in the picture!) actually had couple of solder bridges, so I set that one aside so I could use some solderwick on it later. Also, while the backs are 99% the same between the different version, I noticed I had moved quite a few things around on the 1.2/1.3 revision, so the top stencil simply would not work with the 1.1 board. So it looks like they are either a) Coasters b) in need of a separate stencil, or c) I'll be doing a partial stencil job and do the rest by hand in the near future.

When I went to check the other 2 board, they both seemed fine. I did notice in testing though that for the USB to be seen on my computer I had to apply 12V to the circuit as well (used an old router power supply). That surely is a bit of an inconvenience for further testing, however when doing that my computer was successfully able to open the port and talk to the ELM329 chips.

Next we getting the PCB all connected and built into the housing. I re-used the housing from an existing ELM327 instead of a new one, since that already had some wires connected to the OBD connecter and had a 8 pin plug. After taking off any of the wires we didn't need, soldering a new one to pin 1 for SWCan, and moving the wires to their right spot in the 8pin connector it was ready to go in. I had meanwhile also made a usb cable to connect to the 4 pin connector on the PCB.
The final result looked pretty sharp!

Everything all connected

Yes the RED wire is Ground.... Crazy Chinese people... I didn't bother to change it

Ready to use! Now if only I had a snazzy sticker...

The device defaults to Hi-Speed CAN, and thereby lets you use whatever ELM327 Software you may have that supports CAN commands. A Quick test showed this to work, and when switching over to the SWCan chip, by issuing an 'AT C1' command, we were able to also see data using a terminal app, so it looked like a success!

Next, I will try to build a few more boards , but also perhaps write some software for it to easily interface with it since right now it's really more an 'advanced users only' tool.