Versatile Engine Management Systems - VEMS wiki

This project is in a serious hurry, since they want to race on Oct 12, but the trigger is not supported yet !!!

First we need to find out the trigger arrangement.

So it's VR, with gaps:

• 60
• 90
• 30

degrees. The multitooth.c code should fire a "trigger_tooth" (with the assumption we are 70 degrees BTDC) when the gap=30 degrees is detected. This is not very complex, actually very close to what the multitooth.c tooth_relative_length() ( which is called "multitooth advanced filter", that I use on my daily driver, probably noone else uses it at the moment), it might just take a tiny change and matching config.

Correct trigger drawings:

As you see, the trigger tooth is 70 deg BTDC. And there are two other tooth. So the trigger tooth must be the tooth that is approximately 30 degrees(and +/- some degrees hysteresis)distance after any other tooth. Unfortunately i didn't see the wheel myself. The guy who made the engine has took this photo, and the drawing. And i've checked it with him on phone. So i hope that the round direction is good.

Actually, this is the only arrangement and direction that makes sense: inter-tooth gaptimes of 60,90,30 degrees, and trigger-tooth being after the 30degrees gap.

Nice!

---

Configuration

firmware revision [1.0.27] (or newer required). MegaTune that matches 1.0.23 or even 1.0.19 should match. Just don't adjust primary_trigger variable from MegaTune (it could change for the bad), leave it alone after uploading the correct value from mtt file.

If you change anything from MegaTune, that is on the same page as primary_trigger, verify on LCD or mcd that primary_trigger variable is not screwed.

• primary_trigger=29
  • 1: multitooth is on
  • 8: advanced filter is on
  • 0x20=32: fiatstilo is on

• secondary trigger=..
  • distributor does not need camsync
  • without distributor, camsync must be used! GenBoard/Manual/InputTriggerCamSync
  • wasted spark is OK, use h[2]=00 01 00 01 ..
• config.toothrel_missing=0x4C
• config.toothrel_normal=0x04
• trigger_tooth=00
• another_trigger_tooth=05 # yes, very tricky
• tooth_wheel=03

No change:

• ignchmax=03 # for 4cyl
• rpmk[0]=0b # for 4cyl
• rpmk[1]=b8 # for 4cyl

I commited a fiat-stilo stereo (primary 60,90,30 type + secondary 1 pulse) trigger wav-generator to firmware SVN. The wav-s are OK now (including header), but haven't had time to test it in operation.

As it turned out, the secondary trigger is not 1-pulse originally. Grinder was used to leave only one (big) tooth.

Unfortunately it didn't succeed, the config + setup will be investigated further.

Also, we plan to write code (+config) for the original camsync, which is roughly like 0V at (ATDC cyl1 crankdeg):

• 15..65 (note: mid at 40)
• 220..380 (note: length appr 160 crankdeg)
• note: gap mid at 360+40 = 400
• 420..580 (note: length appr 160 crankdeg)

Document last modified 2006-03-16 04:43:08

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