Nissan CAS trigger (360 pulses)
Old solution was a 24+1 slot trigger wheel as described here: VehicleFitment/Nissan ... plenty of cars are running on these trigger disks. Still a good option, especially above 1.6 million pulses per minute (above 9000 RPM).
Leaving the 360 impulse disk - implementation works well (slightly above 10000 RPM on bench)
- the 4 (or 6) window pulse connected to primary-trigger HALL input
- the 360 pulse signal connected to sectrig HALL input (without any hardware divider !)
- lower filtering capacitor must be used of course, so mention "sectrig=HALL,Nissan360pulse" in the order comment
- See "Nissan special settings" in [VemsTune Help] on how to measure the length of the longest primary trigger window (if you don't know, or want to verify)
Note: everything below is for GEEK / Developers
We'll adjust the TDC-delay (or is it close to 60 crankdegrees which makes most sense ?) in the userfriendly "1-click" triggersetup configuration (bottom of primary trigger dialog)
- after someone writes exact pattern info here (in place of the "..." below, relative to TDC) - from a reliable source or measurement.
Fill in this form (and correct if necessary): signal is normally 0V (according to patent FIG.3 at least), but 5V in the small slots:
- ... - ... deg BTDC cyl1 (high for 24 deg)
- ... - ... deg BTDC cyl3 (high for 16 deg)
- ... - ... deg BTDC cyl4 (high for 8 deg)
- ... - ... deg BTDC cyl2 (high for 16 deg ???) Is this correct or 32 deg instead (=16 pulses)
- the picoscopeshot says windows are 16,12,8,4 smallpulse (=32,24,16,8 crankdeg) with the rising edge (start of the window) is evenly placed every 180 deg. TDC info unknown. In any case, the order seems decreasing window (HIGH) length.
There is also the 6-cyl wheel:
- ... - ... deg BTDC cyl1 (high for .. deg)
- ... - ... deg BTDC cyl5 (high for .. deg)
- ... - ... deg BTDC cyl3 (high for .. deg)
- ... - ... deg BTDC cyl6 (high for .. deg)
- ... - ... deg BTDC cyl2 (high for .. deg)
- ... - ... deg BTDC cyl4 (high for .. deg)
Best I can do right now (Gunni)
Download this
http://downloads.picotech.com/winxp/PicoScope6Automotive_r6_5_78.exe
Then open this file
http://www.megaupload.com/?d=SJVJBNIK
It´s a SR20DET 1997 engine captured trigger input
Should be easily viewable in the Picoscope program.
The low (4/6) pulsecount connected to primary trigger, the 360 tooth divided by 4 (or 8?) connected to sectrig is being implemented. The exact positions "relative to TDC" (!) would still be needed (firmware+configlet will be released when that is written above).
Geek notes
We thought to use a hardware divby4 divider, but when we implemented in v3 firmware, we found that the 360 pulse works perfectly, while the divby4 is not as reliable
- which might be surprising, but is actually the case, no mistake
- so HW divider is not needed (actually divider is not supported) !
- [nissan trigger patent information] explains the syncing methods used by nissan
- because the sync pulse is mostly 0 (and high for only a short time), the active-high reset input of the HCF4024 seems suitable
- according to MembersPage/JannoKusman/NissanTrigger both edges of the 4-window (or 6-window) signal must be sensed...
- yes, the implementation works that way.
See also