Ignition input question

[MurrayA4]

I am about to install a V3 board MSII which I have set up for Hall Sensor input and direct coil control.In the MSII assembly instructions I ran across the following warning:


ignition input signal needed for MegaSquirt-II versus MegaSquirt:
·MegaSquirt needed one signal per ignition event, but the timing was not critical.
·MegaSquirt-II needs one signal per ignition event, but this signal MUST occur at the advance offset with respect to TDC.
So you CANNOT use the negative side of the coil to trigger MegaSquirt-II because the coil already has timing advance built in, and using it for a timing signal will screw up the total advance severely. You must use the appropriate distributor or crank wheel for your ignition module.

I intend to start with fuel only and searching this forum I have confirmed that I can use the coil negative terminal initially.Do I send this signal to pin 24 of the DB37 for now and then remove and replace with Hall input when I'm ready for ignition control ?I guess what is throwing me off is the phrase "this signal MUST occur at the advance offset with respect to TDC"

My understanding is that I will "lock down" my distributor and using the actual TDC signal fom the Hall sensor MSII will control the static and dynamic advance based on the tables I build in MT.So what is meant by advance offset etc..?

[daniel505gti]

I have done exactly the same thing.
You need to install the components for negative coil trigger input (no ignition control) and then when you’re ready to incorporate ignition re install / remove components for square wage input.

I just ran threw the mega squirt manual and configured the board for negative coil trigger.

Then for ignition control run threw the manual again and set it up for square wave and ignition.

Hope this helps.

[jsmcortina]

When running fuel only you can trigger off the coil (-) just fine like the Megasquirt 1 did.
The warning only applies when you try to control ignition.

James