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Topic: Homebrew 2-stroke ignition? (Read 7659 times) previous topic - next topic

PeterH

I seem to remember that it is possible to do an analog read asynchronously if you access it at a lower level than the normal API. But that would be academic if you are using an interrupt-based scheduling mechanism for your sparks, which I agree seems the only feasible way to meet your timing requirements.

peeprada

Just little bit theory of ignition.
Ignition angle is used only because this is most convenient way to ignite fuel air mixture. When using microcontroller, there is no need to stick with calculating ignition angle specifically.

What matters is burning time. Air-fuel mixture must be allowed to burn completely through by the time exhaust opens. Also, what might be even more important is maximum pressure during burning pressure, that must be achieved right after upper dead point.
Burning time does not depend on RPM or engine load. It depends on air-fuel mixture pressure at ignition and air-fuel mixture ratio. Deviation from optimal mixture causes it to burn slower. Burning speed depends also on mixture temperature. It means, microcontroller need to know throttle position along with cylinder and ambient air temperature.
Code is magic of thinking

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