[Diy_efi] Traction Control System (update 2)

[Perry Harrington]

Doing the D -> A -> D is totally uneccessary.

You are getting digital pules from the 339.  You need only count the falling
edge to falling edge time.  I'm sure the PIC could do this.

--Perry

On Sat, Apr 27, 2002 at 02:10:51PM -0700, Crescent Kao wrote:
> First and foremost, I'd like to thank everyone for the amounts of input you
> have provided. You've all been a great help and wealth of information thus
> far.
> 
> Ok, before I dive into more of what you've all suggested, I counted the ABS
> teeth on the CV joints. Keep in mind again that the test vehicle is an Acura
> Integra using OEM axles. There are 50 teeth on the front and on the rear
> joints.
> 
> Now.. reiterating your suggestions, the ciruit should now look like this (if
> i understand it correctly):
> 
> 
> Using the LM339, it has 4 input comparators that will transform the ABS
> signal (frequency from each wheel) to a usable square wave. I will then need
> 4 x LM2907 units to convert each channel from a frequency to a usable
> voltage. (the LM2907 has a built in op-amp?) Then I will need an AtoD to
> produce a DC signal from which I can then send via the RS232 using an UART?
> 
> 
> Do I have this correct? I poked around about PIC programming and found a few
> sites pertaining to programming PIC chips. I realize that you must program
> in ASM but I did find a site mentioning that you can program using C/C++ and
> compile it for use on a PIC (which I would prefer). Anyone have information
> on this? Using the PIC route sounds promising, but I'd be lost again as to
> how to incorporate this PIC into the hardware.
> 
> Thanks!
> 
> 
> Crescent Kao
> Director of Marketing and Sales
> www.c-speedracing.com
> 
> 
> 
> 
> -----Original Message-----
> From: diy_efi-admin at diy-efi.org [mailto:diy_efi-admin at diy-efi.org]On
> Behalf Of Perry Harrington
> Sent: Thursday, April 25, 2002 6:58 PM
> To: Diy_efi at diy-efi.org
> Subject: Re: [Diy_efi] Traction Control System (update 2)
> 
> 
> On Thu, Apr 25, 2002 at 07:05:35PM -0700, Crescent Kao wrote:
> > Perry,
> >   You are correct... Typo on my part.. the signals are actually 70mV at 1
> > tire revolution per second.
> > I hopped onto NSC website and looked at teh LM339. To be honest - its all
> > cryptic to me <grin> I see that it has 4 inputs and thats about all I can
> > get out it.
> 
> The 339 is a quad comparator.  I turns on at a set voltage.  If you set it
> to turn on at ground, it'll turn off when it detects the ABS sensor output.
> Meaning the output will be an inverse square wave of the AC signal from the
> ABS sensor.
> 
> BTW, how many pulses do you get with 1 tire rev?  I have experimented with
> VSS sensors and they are about 8 pulses per rev, with 1rev/sec being the
> lowpoint cutoff of my existing (non 339) detector circuit.
> 
> >
> > If I understand it correctly, the LM339 will take an analog AC signal and
> > convert it to DC? Even at 70mV would it require a opamp to bump up the
> > voltage still?
> 
> I wouldn't think so, it's a fairly sensitive piece.  The 339 is operated at
> circuit voltage, so you don't need any conversion logic.
> 
> >
> > Also, what does this Hitachi H8 etc do?
> 
> The H8 is a programmable microcontroller.  I'm using one for a project I'm
> working on.  It is probably the least expensive development board you'll
> find.
> It is more than capable of processing the 4 inputs from your ABS sensors.
> 
> >
> > Thanks.
> >
> > Crescent Kao
> > Director of Marketing and Sales
> > www.c-speedracing.com
> >
> 
> --
> Perry Harrington             Linux rules all OSes.               APSoft
> ()
> perry at apsoft dot com 			                 Think Blue. /\
> 
> Those who would give up essential liberty to purchase a little temporary
> safety
> deserve neither liberty or safety. Nor, are they likely to end up with
> either.
>                              -- Benjamin Franklin
> 
> 
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-- 
Perry Harrington             Linux rules all OSes.               APSoft      ()
perry at apsoft dot com 			                 Think Blue. /\

Those who would give up essential liberty to purchase a little temporary safety
deserve neither liberty or safety. Nor, are they likely to end up with either.
                             -- Benjamin Franklin


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