|Bit of a read, so bear with me.
Just for any with interest. First fully functional prototype PCB is built and firmware written. Unit powers on and lights up the green power led for first 6 seconds.
It persistently monitors the two MAF inputs and checks if the voltage is greater than 0.3V and less than 5.12V. If not, the red led blinks once per second if channel 1 fails, blinks twice if channel 2 fails, and blinks 3 times if both fail.
Initial testing of the sum/average mode is coming out spot on. This has been on the bench top. I want to do a full sweep across the range to make sure everything looks good. Watchdog timer is also set and running in the event the uproc glitches and needs a reset.
Connector is an IP67 rated automotive 20 pin connector for connecting the 3 four wire connections to the MAFs and the body harness. The remains pins support the SWD interface for firmware upgrades and/or development.
All parts on the board are automotive rated parts and the power input can accept up to something around 24 or 32 volts. It also has reverse bias protection in the event someone manages to connect the power wrong despite a keyed connector.
Next step is putting together the harness so I can plug it into the car and do a field test. Got all the parts, just short on time.
One thing I never understood about the Selin unit was if it could output voltages greater than 5.12V in summing mode. Expanding the MAF map to support twice the flow rate puts it somewhere just above 6V. However, I limit the output in either sum or average mode to 5.12V since I assume anything greater than that may damage the ECU. I can easily allow the higher voltage range as well as an expanded MAF table if there is need. If anyone knows I’d be interested in knowing.