rusefi.com

I have a 10th anniversary edition Mazda Miata, with FM2 Turbo Kit.
Due to local laws I need to be able to pass emissions via ODB-II so I am leaving the OEM ECU installed.
I have mapped out the OEM ECU's CPU Pins I need and I'm going to pass the Crank/CAM Trigger Info to the STM32,
Then I'll connect the output to the Injectors and Spark from the OEM ECU to RUSEFI. I'll let the OEM ECU/CPU handle
alternator, idle, EGR control.

First I need to step down everything to 3.3V from 5V for the STM32.

our boards have resistor dividers behind an op-amp for isolation, that allowed me to run rusEfi as a datalogger while stock ecu was still getting true readings. I think the 3v thing is already covered.

This might be of interest. http://rusefi.com/forum/viewtopic.php?f=4&t=454