VSS input for Microsquirt

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Tassuperkart
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VSS input for Microsquirt

Post by Tassuperkart »

Ive searched and found a few older threads covering this. Ive found lots of speculation and 'this might work" kind of thing.
So far, devise a circuit to convert TTL signal to analogue 0-5v and feed that to the Squirt seems straightforward and then feeding a CAN devise a VSS signal and using that. I have no experience with CAN
I dont want any specific funcionality, other than just a method of logging vehicle speed only.
Any speed gurus here had any joy and can advise me?
Thanks
The older we get, the faster we used to be...

1980 Ducati 900SSD injected with Microsquirt.
grom_e30
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Re: VSS input for Microsquirt

Post by grom_e30 »

i have not done this my self but if its only for logging you could make a frequency to voltage converter then feed the 0-5v signal from that to one of the spare adc in the ecu you could display that in tunerstudio and also datalog the info. so in theory 0v = 0 mph 5v = yor max mph. shouldn't need to involve the canbus for this but you will need to make a custom .ini to decode and datalog this.

or android apps like shadowdash can log speed via the gps on the android phone / tablet but you get a slower update on this method.
1990 bmw 320i daily driver with m20b25 ms3 sequential fuel, 380cc injectors, d585 coil near plug, home made cam sync, launch control, fan control, vss, homebrew egt logging what's next????
Blown88GT
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Re: VSS input for Microsquirt

Post by Blown88GT »

Microsquirt or Microsquirt Module inside ECU?
My MS Module Module ECU (DIYPNP V1.5) has the interface built in using a LM1815 VR conditioner.

Currently, the VSS sensor is not connected. Need to add 2 wires inside the ECU.
Thought about doing it, but don't know what the added value would be.

Forum member JBPerf sells the interface module.
http://jbperf.com/dual_VR/v2_1.html
1988 Mustang GT, 59k miles, Orig Owner
ProCharger 600B I/C, 12psi, FRP Hdrs, Flwmstr F2, 3G Alt, Contour Fan & DCC, 3.55's, Prog Sprg, Subfms, UCA, LCA, FCA, Tokico 5's, Bridgestone RE-71R 245/40R17, Crane HI-6, Kirban FPR, MS2, DIYPNPF60, Spartan 2, C&L76mm blo-thru MAF, 47lb FRP-LU47
grom_e30
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Re: VSS input for Microsquirt

Post by grom_e30 »

the problem is ms2 based ecu's cant do vss its a ms3 only feature the only way you could do it on a ms2 is with an adc. the lm1815 circuit wont work as the ecu can't read it
1990 bmw 320i daily driver with m20b25 ms3 sequential fuel, 380cc injectors, d585 coil near plug, home made cam sync, launch control, fan control, vss, homebrew egt logging what's next????
Blown88GT
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Re: VSS input for Microsquirt

Post by Blown88GT »

It can be read on my MS2 because it has the extra input circuitry.
https://www.diyautotune.com/support/tec ... ypnp-v1-5/
MM has VR Inputs & Tach Out.
VSS is an AC signal which goes to the LM1815 (Adaptive Variable Reluctance Sensor Amplifier) which outputs to MM VR Inputs.
1988 Mustang GT, 59k miles, Orig Owner
ProCharger 600B I/C, 12psi, FRP Hdrs, Flwmstr F2, 3G Alt, Contour Fan & DCC, 3.55's, Prog Sprg, Subfms, UCA, LCA, FCA, Tokico 5's, Bridgestone RE-71R 245/40R17, Crane HI-6, Kirban FPR, MS2, DIYPNPF60, Spartan 2, C&L76mm blo-thru MAF, 47lb FRP-LU47
grom_e30
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Re: VSS input for Microsquirt

Post by grom_e30 »

i'm sorry to say it cant be read directly on a ms2, the lm1815 is a vr conditioner, (i built one for my ms3 front wheel speed of a vr abs sensor works great) it will take the vr ac voltage and convert it in to a nice square wave.... you then have a nice signal that the ms2 firmware is not able to process as there is no support in the firmware for it.
1990 bmw 320i daily driver with m20b25 ms3 sequential fuel, 380cc injectors, d585 coil near plug, home made cam sync, launch control, fan control, vss, homebrew egt logging what's next????
Blown88GT
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Re: VSS input for Microsquirt

Post by Blown88GT »

I see why now.

Found a thread on this subject.
http://www.msextra.com/forums/viewtopic ... 01&t=48607

This summarizes it:
racingmini_mtl wrote:The only way to get a speed input with an MS2 is to use a spare ADC input and use a frequency-to-voltage circuit. You can't use a digital input for speed because that would require a timer input and there are none available for this on the MS2.
Another option is to use a CAN device such as my I/O Extender. Or you could go for an MS3 which does have support for this.
Jean
I think what this means is MS2 uses a software timer & MS3 uses a hardware timer.
Software timer is interrupt driven, so accuracy is not guaranteed.
1988 Mustang GT, 59k miles, Orig Owner
ProCharger 600B I/C, 12psi, FRP Hdrs, Flwmstr F2, 3G Alt, Contour Fan & DCC, 3.55's, Prog Sprg, Subfms, UCA, LCA, FCA, Tokico 5's, Bridgestone RE-71R 245/40R17, Crane HI-6, Kirban FPR, MS2, DIYPNPF60, Spartan 2, C&L76mm blo-thru MAF, 47lb FRP-LU47
grom_e30
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Re: VSS input for Microsquirt

Post by grom_e30 »

yeah jean has it all explained in the quote.

there is nothing stopping you from feeding the vr sensor through say a lm2917 (frequency to voltage converter) and sending the output on to a spare adc channel to get speed that way

there is a circuit here: http://www.msextra.com/doc/ms1extra/antirev.html
1990 bmw 320i daily driver with m20b25 ms3 sequential fuel, 380cc injectors, d585 coil near plug, home made cam sync, launch control, fan control, vss, homebrew egt logging what's next????
Tassuperkart
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Re: VSS input for Microsquirt

Post by Tassuperkart »

Thanks for the info men. I sort of had that feeling that it wasnt possible to purpose a spare ADC for the task but time passes and there may have been something done.
Ill check out the circuit and see what i can do.
Im capable of building electronics but I cant design/customise it.

Cheers
Evan
The older we get, the faster we used to be...

1980 Ducati 900SSD injected with Microsquirt.
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