Spare ports to monitor 0-.5 volts for data logging

[1983sc]

I'm interested in using MS 2 spare ports to monitor input from my twin ignition systems in the range of 0 to .5 volts. Each of the twin ignition systems provides a linear signal where .1 volt equals 10 degrees of advance, .3 volts = 30 degrees, etc. I'd like to route these signals to MS 2 spare ports for data logging. Can anyone suggest which ports to use and how to configure the code to read and display the signal? Thanks

[Bernard Fife]

1983sc,

The spare ports are configured as outputs, not inputs. You may be able to use other unused pins to monitor a voltage, but this depends on which pins you are currently using, and which code you are using.

For example, you might be able to use the 'full-time baro/EGO2' pin (AD6 - jumpered to JS5) or the 'Knock/MAF' pin (AD7 - jumpered to JS4); if you aren't using these. For a 0-5V signal, you would need to copy the EGO circuit, which consists of a couple of resistors (1K and 1M) and a capacitor (0.22uF). You can do this in the beta area of the V3 board.

You could bring the signal in on one of the unused DB37 pins (these are connected to SPR3 (pin 5) and SPR4 (pin 6))

All the hardware details you need are here: http://www.megamanual.com/ms2/pcb.htm

The knock channel reports the voltage directly as 'knock' and you can add this to your datalogs in the [Datalog] section by adding a line like:

Code: Select all

   entry = knock,  "myVolts",       float,  "%.2f"

EGO2 does not report the voltage or ADC count directly. So you would have to work with the settings in TunerStudio (and/or adjust the INI's OutputChannels section) to get the output signal to reflect the actual voltage.

Lance.