Some may know i have previously requested the Toyota 24 + 2 (should we call it that?) trigger to be implemented into the code.
To further aid this, i have done some research with oscilloscope and dived into how the trigger is wired to the OEM ECU.
I have used the distributor from a european Toyota Celica with an NA 3S-GE engine. Some say the 4A-GE and many other toyota engines have the same type of trigger but i can not confirm that though as i only have the 3S-GE stuff readily available.
This distributor contains one 24 teeth trigger down at the bottom of the dizzy. No missing tooth. And on top, there's 2 additional trigger sensors that are located on each side of the dizzy. One of these extra trigger sensors is placed at the 0 degrees TDC point and the other one at the 360 degrees TDC point (crank degrees).
All of these triggers use the same ground. I don't know if this is a problem though. At least it worked fine picking up the signals on my OWON oscilloscope using a power drill at what i believe is far higher speeds that what a camshaft operates at. The images provided of the signals though are taken at sensible speeds.
The cam sync lobe seem to have two trigger points. One that i would call the primary trigger, a very sharp pointy tooth. And then it has what i would call a "dip" at the other half of the lobe. Maybe this is nothing to be concerned about though. I don't really know if a MAX9926 would pick up that dip on the lobe as a triggering signal. See images of it below.
Heres an image of the 24 teeth trigger wheel inside the dizzy:
Heres a detailed image of the cam sync lobe. Both the pointy sharp primary trigger and the "dip" on the other side:
This image describes the actual signals. In this particular one, Channel 1 (RED Curve) is the 24 teeth signal, and Channel 2 (BLUE Curve) is the signal coming from the cam sync trigger sensor located at the 0 degrees TDC point. It also shows a dip in the sync signal when the dip on the lobe passes the trigger sensor:
In this image i have provided a signal i discovered practically by accident when by mistake connecting both cam sync trigger sensors to the same probe. This signal seems pretty similar to the Audi 135 trigger with one seperate signal every crank turn on top of the constant analog signal from the 24 teeth trigger. The difference being that instead of 135 teeth per revolution, there's only twelve. Although i would believe the previous signal using only one sensor for syncing would be more reliable and maybe even easier to write a decoder for since that signal can tell you exactly when the engine has made a complete cycle, instead of a half one, having the ECU not really know what cycle the engine is in:
And here's a zoomed in image of the same signal, using both sync trigger sensors on the same probe. Although i believe the speed is slower here as well seeing as the signals produce far less voltage than before:
So, think this trigger would be possible to implement into the code?
Personally i believe the method of using only one of the sync trigger sensors would be the best way to go because, as i said, it would be able to tell the ECU when the engine has done a complete cycle. Maybe making it possible to eventually run fully sequential.