@dmaxben Personally don’t believe there is nothing wrong with the M2 implementation. It should work fine.
The chip I mentioned that you already have works as a transceiver and handles the actual electrical connection and signals. You just have to build a controller to handle those signals.
I think if someone were building a stand alone VPW device this would be the way to go. (Maybe even worth taking the M2 processor board and building a separate interface board for it for JUST the VPW)
But realistically the M2 can handle the work.
What your likely looking at is the transceiver will just return the 1’s and 0’s and you have to sort them out. It looks like its a simple UART connection. The controller has to be able to manipulate the bits and figure out the frame. So you look for specific patterns as outlined in the J1850 documentation and go that route.
With the M2 you have to actually do the transceiver work too. Since there are some extra electronics on the pins they have them on it shouldn’t take long to actually accomplish it. You can build a blocking interface first to work out the details and once you have that working go back and refine it to not be blocking so it can be used with the M2RET interface.
It would be reasonable to expect to be able to build a library that could use the chip you have as the transceiver and also build one without it controlling the pins directly. Might not be a bad way to go actually to build the library from this chip then build a transceiver in the M2.
I do have a Due board here with a prototype shield…
What did you actually have to use to make it work for additional hardware?
Probably wouldn’t use it in my truck directly but worth working towards the ultimate goal.
