[Diy_efi] Traction Control System (update 2)

[Axel Rietschin]

Yes, definitely, you have to count the pulses (the zero crossings, actually)
not measure "AC voltage" which means absolutely nothing by itself. If you
want to convert the pules to a voltage, you may use a device like the LM2907
(thanks, Brian)

http://www.national.com/ds/LM/LM2907.pdf

When you have a voltage ratiometric to the pulses frequency, you may convert
it to a digital value using an A/D and send the value over RS-232. Some
microcontrollers have built-in A/D converters and UARTS, this may help.

You have to determine your speed range and the needed resolution; with a 8
bit A/D and 0-200 km/h range, you'll get 0.78 km/h increments.

--Axel

----- Original Message -----
From: "Lachlan Chapman" <chapmans at ihug.co.nz>
To: <Diy_efi at diy-efi.org>
Sent: Friday, April 26, 2002 2:27 AM
Subject: Re: [Diy_efi] Traction Control System (update 2)


>
> I dont think the voltage will be increasing, if i were you i would probe
it
> with an osciiliscope to see the frequency of the pulses
> ----- Original Message -----
> From: "Crescent Kao" <crescent at c-speedracing.com>
> To: <Diy_efi at diy-efi.org>
> Cc: <noltez at c-speedracing.com>; <sailwhatcom at hotmail.com>
> Sent: Friday, April 26, 2002 12:16 PM
> Subject: [Diy_efi] Traction Control System (update 2)
>
>
> > Ok.. we've made a little more progress on the traction control system.
> > Here's a recap of what we have so far:
> >
> > . Test vehicle - Acura Integra with ABS
> > . Signals generated from the ABS sensors - 0.7mV AC (and up, depending
on
> > speed)
> > . Probing the ABS wires at the ABS brain verified the signals. The AC
> > voltage increases as speed increases. (around 1.4mV at 35mph
> >
> > So... at this point we were looking into how to convert the signal to a
> > digital signal and read it via a serial connection (RS232) to an onboard
> > laptop.
> >
> > This is what we have so far hardware wise:
> >
> > . using an op-amp, bump up the 0.7mV+ input signal (above 1v?)
> > . then convert the AC signal to DC
> > . convert the analog signal using an AtoD processor
> > (perhaps NSC ADC08034 http://www.national.com/pf/AD/ADC08034.html 4
> > inputs -
> >   however it specifies that it interfaces using "Microwire". I have no
> idea
> > what this is. Should we use an   AtoD that uses parallel interface
> > instead?)
> > . format the signal to a usual datastream
> > . send the data via UART (9600 or 11500 baud) to the RS232 port
> >
> > This is our current challenge. Does this approach sound correct?
> >
> > Crescent Kao
> > Director of Marketing and Sales
> > www.c-speedracing.com
> >
> >
> >
> >
> > _______________________________________________
> > Diy_efi mailing list
> > Diy_efi at diy-efi.org
> > http://www.diy-efi.org/mailman/listinfo/diy_efi
> >
> >
>
>
>
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