MAF and knock

[mrbell]

So, unless I'm totally blind today, it seems there is no knock capability on the uS. I was looking over the documentation on how to set up the MAF, so I'll be ready when I can get my hands on the uS.
If one goes pure MAF, is a barometric sensor needed? It would seem that this would be a bit redundant, so is it feasible to jump the Spare ADC to a knock sensor instead?
If this has already been covered, I apologize. I searched but couldn't come up w/ anything conclusive.

[MegaScott]

So, unless I'm totally blind today, it seems there is no knock capability on the uS. I was looking over the documentation on how to set up the MAF, so I'll be ready when I can get my hands on the uS.
If one goes pure MAF, is a barometric sensor needed? It would seem that this would be a bit redundant, so is it feasible to jump the Spare ADC to a knock sensor instead?
If this has already been covered, I apologize. I searched but couldn't come up w/ anything conclusive.

Normally the knock signal would go into the PA0 line pin 26 of the HCS12 processor, unfortunatly it doesn't appear to be hooked up to anything.

At least by the looks of the Megatune .ini file the code for knock appears to still be in there.

You could possibly rewrite code to change the the port assignment, or do a little steady hand rework of the board to jumper pin 34 to pin 26 of the CPU.

[grippo]

Although PA0 is commented in the code as "Knock Enable" signal it isn't used at present. It was intended to work with a GPIO board with knock sensing capability. The knock sensing software works from pin ADC-7, but there were not enough pins on the Ampseal connector to handle this, so it is left unconnected. If you find some pin on the Ampseal that you didn't need, for example the second ignition input or output, then you could cut that trace to the Ampseal pin and solder in a tiny wire from that pin to the ADC-7 pin on the processor. This is not at all difficult to someone who does pcb soldering for a living, but you really need a tiny tip on the soldering iron and some experience. If this were done, the software is in place to use the knock sensing data.

[MegaScott]

Good idea Al, I think I'll try it, I need knock sense on my truck, but I don't need two channels of ignition.

I can post pics when I get it done.

[mrbell]

Just to clarify something about the dual spark setups. You can have 1 input w/ 2 outputs, correct? And take the pin for the 2nd spark input and use is as knock enable(w/ some board modifications)?
would that be the opto in pin on this diagram:


There seem to be some discrepancies on taht diagram vs what I'm seeing as features on the forum...

[grippo]

No - the opto input is the first input. You want to use VRIN2+, pin 4. But note that you can use any other unused pin also, for example the flex fuel pin. The important thing is to be sure there is a trace going to the pin, either from above or below, and cut it by scraping on it with a sharp awl. If you don't see a trace, it may be embedded in an inner layer, in which case you must cut the pin itself. Don't use a ground pin because I believe that all of these are needed - unlike with the V3 board.

[mrbell]

Excellent. Thank you.