Originally Posted by muythaibxr
The inverted vs non-inverted output terminology goes back to when the LED-style outputs were "normal" and connecting to VB921 or other IGBTs were "inverted."
All grieving aside, I've honestly never understood the use of the terminology, even in this environment.
Going back to the VB921 design, a positive voltage applied to the "input" terminal of the 921 from the CPU causes the 921 to turn "on", which allows current to flow through the coil.
In such an environment, one must set "Spark Out Inverted" to "Yes."
Do you have any recollection of what the rationale behind that nomenclature was? To me, the word "inverted" would imply something other than the "normal" method of operation, which even back then was for the CPU to raise one of its output pins high when it wishes for the coil to operate. From the CPU's point of view, "high" = coil on, and "low" = coil off. And yet that is what got called "inverted".
In other words, my "improved" spark driver works precisely the same way as the very first ignition-capable Megasquirts did. And yet in both systems, "inverted" means that the ignition coil follows the state of the CPU output pin controlling it, rather than being inverse of it.
I've never understood why the nomenclature was written that way. It only makes sense if the "inverted" vs. "non-inverted" nomenclature wasn't coined until people started using the LED circuits to drive wasted-spark coils with on-board igniters, in which case (assuming the "standard" circuit) the "non-inverted" nomenclature makes sense, not from the point of view of the CPU, but from the point of view of the inverting output driver.
But as you said, the term supposedly predates this.