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Old 09-28-2009, 12:47 PM   #1
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Default Spark settings inverted?

What exactly do the spark inverted yes/no settings change?

I this a change to rising/falling edge trigger?

Ron
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Old 09-28-2009, 12:50 PM   #2
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Old 09-28-2009, 12:56 PM   #3
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That setting changes the output polarity of the spark output driver, specifically, whether the CPU pins used are high in the "resting" state and go low during the "dwell" state, or vise-versa.

In the "usual" configuration, the output driver circuit is inverting, such that the output is high (and thus, the coil conducts) when the CPU pin is low. (This is why coils fry during a reflash, and why some cars pop at poweron). In this configuration, you must select Inverted = NO (which is somewhat counter-intuative.)

In my "improved" output circuit (linked to above), the spark drivers are non-inverting (technically, they are double-inverting) so that when the CPU pin is low (or the CPU is inactive) the final output is also low. In this configuration, you set Inverted = YES (which, again, is silly, but it's the way it is.)



The primary input trigger (on the MS1) is always falling-edge detect, with respect to the CPU itself. This is due to the fact that the pin used for the primary trigger is the hardware IRQ line, and the CPU is "hard-wired" to only look at falling edges on that line. Inversion at the input circuit must be taken into account in determining whether this corresponds to a leading or trailing edge.
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Old 09-28-2009, 08:12 PM   #4
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Thanks for the responses, that's what I needed to know.
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Old 09-28-2009, 10:08 PM   #5
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Ipsa scientia potestas est.
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