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By metcap
#66136
Ok so the coil driver sits between the output of the tc4424 and the spark plug, so if I scope tc4424 output vs spark event at spark plug won't tis show any delay totalled all the components in between including the coil driver? I did mention above that I saw only minimal delay.
.Exactly why would we care?
:) I was asked to put up some data or get out (not these exact words) so at least others can look over or maybe test. Maybe we come to conclusion that Max chip doesn't do so good in A2 mode (still waiting for ur answer which mode I shud try), I dunno but I do have some hope of maybe others helping to understand this but I'm sure they have better things to do. In the mean time I'm still daily driving this :P
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By PSIG
#66139
metcap wrote: Mon Dec 04, 2023 11:29 pmstill waiting for ur answer which mode I shud try
Zero-crossing with no adaptive threshold. Yes, mode B.
By JHolland
#66142
metcap wrote: Mon Dec 04, 2023 11:29 pm Maybe we come to conclusion that Max chip doesn't do so good in A2 mode (still waiting for ur answer which mode I shud try)
I've never seen a problem with A2 mode, B mode can be noise prone if you're not setting an external threshold for arming the trigger.
'Minimal delay' isn't very useful, anything over 50us is going to cause a noticeable drift.
The effect of the filter capacitor on the input is difficult to determine with a compound waveform like yours, I would certainly try it without.
By miker
#66148
Can you scope the pin on the speeduino board so we see the signal speeduino is generating and narrow down if the problem is speeduino output or something else.

I've tested speeduino output in the development environment (ok I'm testing Arduino not speeduino to be technically accurate) and I see a much much smaller delay. The actual delay is dependent on the decoder but 4 to 10us over a single spark event (so 720 degrees).
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By jonbill
#66152
At the risk of repeating myself, the different delays at 1k rpm and 5k rpm are ( it looks to me) the same number of degrees - about 3 to 5.
Its unsurprising that the same number of degrees of rotation take less time the faster the wheel rotates, and its unsurprising that spark events happen at different numbers of degrees offset from an arbitrary tooth edge when changing the trigger angle.
What am I missing?
By metcap
#66156
miker wrote: Tue Dec 05, 2023 4:33 pm Can you scope the pin on the speeduino board so we see the signal speeduino is generating and narrow down if the problem is speeduino output or something else.
You mean the signal from Speeduino ign pin to TC4424 right? I'll try to get something this week.
By metcap
#66157
jonbill wrote: Tue Dec 05, 2023 5:35 pm At the risk of repeating myself, the different delays at 1k rpm and 5k rpm are ( it looks to me) the same number of degrees - about 3 to 5.
Its unsurprising that the same number of degrees of rotation take less time the faster the wheel rotates, and its unsurprising that spark events happen at different numbers of degrees offset from an arbitrary tooth edge when changing the trigger angle.
What am I missing?
I think 300us at 1k rpm is 1.8deg and 60us at 5k is 1.8deg so you're right that the time error gets smaller the higher rpm we go for a fixed degree. But in this case if theoretical there's no error, then if we trigger at 0 deg or 180deg (or whatever angle we choose) the spark event should be on mark since I've a 12-1 wheel. Problem I'm seeing is there's almost no error at 0 deg and increase as I get to 180deg.
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