> Can you summarize the requirements? Input trigger
> and
> output spark timing (the ign-advance is from table +
> added retard of course).
On the 2nd generation Mazda rotaries (1986 thru 1991), the input signals are provided by two inductive pickups in the Crank Angle Sensor (CAS). The CAS contains two reluctors, one with 24 teeth, and the other with two teeth. As I write this, I'm remembering an on-line article that provides these details better than I could:
http://www.teamfc3s.org/info/articles/demystifying.html
This covers the stock ignition system in some detail. Ideally I would like to retain the stock CAS, igniters, and coils, and drive them with a new controller.
Very good intro indeed.
So you have 2 rotors, with 4 sparkplugs: 2 leading and 2 trailing plugs. The leading plugs are fired simultaneously, the trailing plugs are fired alternating.
Translating to GenBoard usage and programming:
- feed the 24 teeth/CAS to IC3 input
- feed the 2 teeth/CAS to TACH (INT6) input
- write the phase-calculation (timing.c)
Stock Coil/Driver Configuration
This uses the factory Mazda leading and trailing coil packs, with integrated drivers.
| Coil | Firing Mechanism | Note |
| Leading Coil | 5v digital output to IgT controls firing and dwell. | Waste spark configuration; one coil fires the plugs on both rotors. |
| Trailing Coils | 5v digital output to IgT controls firing and dwell. 5v digital to Select line controls which rotor to fire. | One driver is connected to two coils. Which coil fires depends on the state of the driver's Select line. |
Dummy Coil Configuration -- Wasted Leading Spark
This configuration uses 3 coils total. One for the leading, and two for the trailing.
| Coil | Firing Mechanism | Note |
| Leading Coil | IGBT in genboard fires coil and controls dwell. | Requires a two post coil, because of wasted-spark configuration. |
| Trailing Coil (Front) | " | Connected to trailing spark plug in front rotor housing. |
| Trailing Coil (Rear) | " | Connected to trailing spark plug in rear rotor housing. |
Independent Coils -- Independent Coil Packs
This configuration uses four independent coil packs. It is the least sophisticated coil configuration, and would be the easiest to implement using existing hardware and software support.
| Coil | Firing Mechanism | Note |
| Leading (Front) | IGBT in genboard fires coil and controls dwell. | |
| Leading (Rear) | " | |
| Trailing (Front) | " | |
| Trailing (Rear) | " |
Advance calculations could come from a single table, with the trailing timing fired at a user-selectable (degree) delay after the leading.
> I'm writing a more generic trigger and output handling for the MS-AVR GenBoard and might just as well make it suitable....
See also: InputTrigger