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Hi Guys
I have been busy with other projects, but have managed to do some testing of the MIMA_C in my car. (no test pilot volunteer yet)
As soon as the MAP , TPS, and Battery amps signals were all connected to the MIMA board, I began to have unreliable A/D conversions and could see with the scope that the problem was due to high frequency noise spikes between the individual module grounds. The signals all need to be read by the MIMA A/D converter, so they needed to be brought to a common ground in the MIMA . Several simple ferrite bead and differential input schemes were tried, but none truly isolated the signals, or removed the noise. I finally decided to go all the way, and have designed a full precision optically isolated input for the three signals that should solve this problem, and let me get back to the software and final board layout issues.
http://pages.cthome.net/genesisone/index.htm
Thanks for your patience.
:wink:
I have been busy with other projects, but have managed to do some testing of the MIMA_C in my car. (no test pilot volunteer yet)
As soon as the MAP , TPS, and Battery amps signals were all connected to the MIMA board, I began to have unreliable A/D conversions and could see with the scope that the problem was due to high frequency noise spikes between the individual module grounds. The signals all need to be read by the MIMA A/D converter, so they needed to be brought to a common ground in the MIMA . Several simple ferrite bead and differential input schemes were tried, but none truly isolated the signals, or removed the noise. I finally decided to go all the way, and have designed a full precision optically isolated input for the three signals that should solve this problem, and let me get back to the software and final board layout issues.
http://pages.cthome.net/genesisone/index.htm
Thanks for your patience.
:wink: