Cpu signal input adjusting

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rukavina
Helpful MS/Extra'er
Posts: 58
Joined: Wed Aug 20, 2014 9:42 pm

Cpu signal input adjusting

Post by rukavina »

I have a square wave signal ~0 to ~5v to my header for vss. I just built 2nd board and did "upgrade" to drac. I tested circuit on bench with sine wave generator and scope. No known noise present. Had good signal. After going from 0 to 1000hz and back down I had 0hz on scope and generator but had around 30hz in tuner studio. I drove today and do have some issue. I am going to pull out and test (play). The question is what can I do to that signal. In line resistor or resistor to ground or inline diode or inline cap or cap to ground. Is there any DONTS

OK my square wave is 4.8 to 1.25v .. I think if I could lower the voltage down a bit I think I would be fine. Any suggestions how to do that cleanly.
Also with nothing connected and jumper off header I get 27hz in ts.
4wheel drive 454 vortec on ms2 w/gpio for 4l80e Trans control
Matt Cramer
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Posts: 17499
Joined: Thu Apr 16, 2009 8:08 pm

Re: Cpu signal input adjusting

Post by Matt Cramer »

A 1.25 volt signal will probably be interpreted as a zero. If it is using an external pull up, try removing the pull up or increasing its resistance.
Matt Cramer -1966 Dodge Dart slant six running on MS3X
rukavina
Helpful MS/Extra'er
Posts: 58
Joined: Wed Aug 20, 2014 9:42 pm

Re: Cpu signal input adjusting

Post by rukavina »

Wound up putting 820k from signal to ground and that dropped my voltage from .98 to 3.5ish and works good. I still have that weird residual low hz with nothing hooked to gpio but does not effect anything.
4wheel drive 454 vortec on ms2 w/gpio for 4l80e Trans control
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