First the question how would you communicate from one gauge pod to a master? My plan was SPI because I have done it before and it doesn't require a transceiver like Canbus. I figured I would ask though before I continue down this path.
So here is the overview of the gauge pod. Atmega 328P-AU, L293D ( I am about drop the 293 for a DRV8833), X27.168 motor. Error light controlled by the ATmega and Backlights that are currently always on. I will probably add control for the backlights in the same revision with DRV8833.
I haven't started the master controller yet. I wanted to pick how I am going to talk to them first and then go from there. Does SPI make sense in this application or should I be looking at something else?
Paul_KD7HB:
How is a gauge pod different from a pea pod? Perhaps begin with a physical description of what you are designing.
Paul
Oh my picture didn't upload it was oversized. Uploaded now. Yes I already have the board but I get them for free so it's no big deal to change the board. So like an automotive gauge.
I believe both I2C and SPI were designed for on board or short distance communication. Tho both have been abused for somewhat longer distances.
I can understand not wanting to use Can-bus but there is a good reason its used in cars. An automotive environment is very noisy which can have a terrible affect on communications. Can-bus provides built-in methods for error checking and redundancy to ensure your messages are received correctly. You would have to discover and deal with these things yourself if using I2C or SPI.
I find using Can-bus is easier and more reliable than using other methods. Which makes the extra hardware worthwhile.
Cannot speak to the STM32 aspect of things but canbus is electrically similar to RS-485.
If you only need simplistic data transfer that is robust enough to work in an automotive environment, RS-485 can provide bumper to bumper distance, SPI and I2C cannot do this without significant changes to the interface.
You can implement your own simple protocol to insure the data gets to where it is supposed to go. It’s not difficult and reasonably fast bus speeds can be used. The 485 bus is multi-drop/multi-master and requires the same biasing and termination resistors as canbus for proper operation.
WattsThat I Just have a bad taste in my mouth trying to make can bus work on existing GM lan buses. ( GM's stupid 1 wire can). I have avoided Can since failing miserably at that project. Its time to face that demon I guess.
garnerm91:
Do you think it might worth switching to a STM32F103C8T6 since they support Can at a hardware level? I would still be programming in Arduino IDE.
It only has the controller, so a transceiver is still needed. I just buy the modules that have both then I can use any micro I like.
It's good to conquer your demons. This is a minor one I think.
