First I need to correct some things in my previous post: there are two ignition pickups in the single dizzies, one for each ignition system. (Some racing rotary's used one but then have both plugs per chamber firing at the same time). Also, points (2 of) were used on early single dizzies prior to the introduction of electronic ignition. It's been a while since I've played with rotary's, sorry.
A rotary will run on either ignition system alone, though poorly on the trailing as the ignition timing will then be retarded by up to 10 or so degrees. In fact, on early models fitted with a thermal reactor - like a catalytic convertor without the catalyst - the trailing ignition was (is?) shut off at times to encourage burning to continue in the thermal reactor for emissions reasons.
They are like a 4 cylinder 4-stroke (or two cylinder 2-stroke) in terms of the total number of ignition cycles per crank or eccentric shaft revolution ie. 2.
A 4-stroke fires, per cylinder, on every second revolution - 1/2 times 4 cylinders = 2 times per shaft revolution. The rotary fires three times per rotor revolution while the eccentric shaft turns three times per rotor revolution = one ignition event per rotor, per shaft revolution, times two rotors = 2 times per shaft revolution. The two plugs (ignition systems) per chamber are to ensure complete combustion in the (odd shaped) combustion chamber.
Because they do fire like a 4 cylinder, (4 stroke) the two setups would be an easy way of achieving the required ignition timing without having to change too much in the ECM. It is not the only way to do it, just easier.
It is only the ignition side that requires duplication, not the fuel, although staging injectors could be easily achieved by setting the duty cycle of the second set to zero until they are required.
If the signal from the Mazda inductive pick ups is similar to that from the GM (Camira, Astra/Pulsar) I think that it would actually be quite straight forward to set up, though I am not 100% on how you would share the inputs from the sensors. Parallel wiring should be OK without me thinking about it too hard. Another alternative may be to use fixed 'sensor' data ie. feed appropriate fixed values into the ECM used for the (less critical in terms of timing) trailing ignition and ignore any cold operation advance etc. You would lock the centrifugal and vacuum advance mechanisms in the Mazda distributor for each side in the most retarded position and operate like Camira/Astra/Pulsar/Commodore V8.
The 'bottom' 'plug is the leading ignition side and the 'top' 'plug is the trailing side and the leading plug always fires first; the rotor rotates clockwise.
