DIY LTCC or similar system for LT1s

[lionelhutz]

I've been trying to figure out what you're describing. The 1-8 demultiplexer made no sense. A 5-bit ripple counter could work by counting the high res pulses each time the low res turns-on.

I assume once you have the count you'll latch it into a chip so it's held until the next count? You need to use a latch signal for this chip that transitions properly when the low res signal goes away.

I would have expected you to use the high res as the clock to the ripple counter. I suppose you could and the high res and low res so the clock pulses only occur when both exist. Definitely use the low res as the input. So, the counter begins counting up during the low res pulse and then when the low res pulse ends you latch the count into the latch chip.

I'm curious how you'll determine between the other 4 cylinders which have the equal 2 high res pulses. I suppose you could keep the count from the previous cylinder and then count the 2 pulse pattern on-top. Cylinder 4 would be 9 counts for example which is a unique count. This means you'd need a counter reset circuit that looked specifically for a 2-pulse pattern to reset the counter.

I'm not sure why you'd want to use the ignition module and then use it to drive another ignition transistor. If you use LS coils you drive them at logic levels since they have a built-in driver.

Best I can tell, the low res signal starts when the corresponding cylinder is at TDC. So, don't forget that you have to switch to the #8 cylinder when you've found the #1 TDC low res pulse so that the PCM can fire the #8 cylinder in advance of the #8 TDC low res signal appearing.

[vilefly]

I've been trying to figure out what you're describing. The 1-8 demultiplexer made no sense. A 5-bit ripple counter could work by counting the high res pulses each time the low res turns-on.

I assume once you have the count you'll latch it into a chip so it's held until the next count? You need to use a latch signal for this chip that transitions properly when the low res signal goes away.

I would have expected you to use the high res as the clock to the ripple counter. I suppose you could and the high res and low res so the clock pulses only occur when both exist. Definitely use the low res as the input. So, the counter begins counting up during the low res pulse and then when the low res pulse ends you latch the count into the latch chip.

I'm curious how you'll determine between the other 4 cylinders which have the equal 2 high res pulses. I suppose you could keep the count from the previous cylinder and then count the 2 pulse pattern on-top. Cylinder 4 would be 9 counts for example which is a unique count. This means you'd need a counter reset circuit that looked specifically for a 2-pulse pattern to reset the counter.

I'm not sure why you'd want to use the ignition module and then use it to drive another ignition transistor. If you use LS coils you drive them at logic levels since they have a built-in driver.

Best I can tell, the low res signal starts when the corresponding cylinder is at TDC. So, don't forget that you have to switch to the #8 cylinder when you've found the #1 TDC low res pulse so that the PCM can fire the #8 cylinder in advance of the #8 TDC low res signal appearing.

1) A 5-bit counter is not available in the marketplace. you have to build it out of flip-flops, and I will never give up precious breadboard space making that which is much easier to do with discrete components. 2 unused pins won't kill you, heh. The demultiplexer is not pictured yet.
2) The nor gate does this already. I even wrote a note about its output.
3) The AND gate turns excessive and fruitless work into a signal I can sync with. Again, this is already done. Who wants to count to 720?
4) The circuit so far is merely for syncing during start. The rest of the time it will be the job of another counter that recycles automatically, coupled to the 1-16 demultiplexer/data selector, because they count 0, and the ripple counter does not. It will clock on the LEADING edge of the low-res optispark signal. (switch to next coil when TDC is reached)
5) I never said I was going to use the oem ignition module. I have 8 transistors at my disposal.
6) I already posted about advancing to the next coil in advance. The optical wheel I posted now has TWO sets of numbers on it.

I don't believe in measuring and calculating on the fly. This leaves you vulnerable to a glitchy signal, and is not very fault tolerant. I am no longer an idealist. Just set the counter, and go.