wb lcd display

[Bill Shaw]

Thanks for the replies guys.

I think I'm OK with the PS section now.  After I sent the schematic I remembered a
bunch of protection in the EFI332 schematic similar to what Bob and Eric
recommended. I'll implement something like that,  with a LM2931 regulator.  The
ferrites will be deleted,  leftovers from the low-power fcc-able design it was
stolen from.

Darrel: Yes,  please do upload the PDF version.

Marc:  50 ma should be far more than it will ever need.  The Orcad (V9) file is in
incoming also - WB_LCD.DSN.

I'll update the schematic and post an announcement when I do.  In the mean time,
I'm looking for constructive feedback on the design.

I have code I'm going to steal for the LCD, A/D converter,  data logging to
eeprom,  and serial monitor.  The boot loader sounds good,  I'll look into that
also.

I don't have the data for the translation table.  I saw some formulas floating
about recently,  has anyone plugged them onto a spreadsheet to generate some
numbers yet?

Regards,

Bill


> Date: Mon, 10 Sep 2001 08:07:28 -0400
> From: "rr" <rrauscher at nni.com>
> Subject: Re: wb lcd display
>
> For the 12 -> 5v p/s, I would do something close to how
> the WB UEGO circuit is powered. Just change the 78L08
> out for a run-of-the-mill 7805 regulator chip. Maybe add
> a 1N4001 diode in series with the input.
>
> I'm going to try to look at the schematic. However I don't
> know how much luck I'll have with the EPS file.
>
> BobR.
>
> ----

>
> Date: Mon, 10 Sep 2001 11:19:48 -0400
> From: Eric Bryant <BRYANTE at ghsp.com>
> Subject: RE: wb lcd display
>
> I'd also recommend the addition of some capacitance to the input and output
> of the regulator (at least a 0.1 uF on the input and output, and I'd
> probably also put about an additional 10 uF cap on the output).
>
> In addition, place a transorb/zener diode in parallel with the input to
> clamp the input voltage to ~30 V or so (if you can resist the temptation to
> jump-start your car off a 24 V supply, feel free to clamp the input to 20 V
> or so).  The series diode and the transorb really need to be used for any
> in-car application, and this is pretty much bare-minimum for operation in a
> vehicle with an internally-suppressed alternator.  It's probably not a bad
> idea to put some small amount of series resistance in the input line,
> either, but this depends greatly on the current demands of the display unit
> (something like 5 ohms works pretty well with a small transorb, but the
> wattage requirements get pretty big if the display unit draws any
> appreciable amount of power).
>
> Eric Bryant
> mailto:bryante at ghsp.com
> http://www.bryantperformance.com
>
>
> ------------------------------
>
> Date: Mon, 10 Sep 2001 10:26:14 -0600
> From: "Dave Mumert" <dmumert at telusplanet.net>
> Subject: Re: wb lcd display
>
> Hi
>
> I checked over the drawing very briefly.  I have used the LCD driver before
> and it works good and is easy to program.  Have you thought of using a boot
> loader for the 16F877?  Check at
> http://www.xs4all.nl/~wf/wouter/pic/wloader/index.html  for a list.  If
> people were to buy the PIC with the bootloader pre-loaded they would need no
> other hardware to program it with their own code.
>
> You might consider using one of the National regulators specifically
> designed for automotive use.  They are protected against reversed batteries,
> double battery boosts and 60V load dumps.  I have been using the LM2931, it
> is cheap and comes in several packages, the only downside is the requirement
> for a 100uF cap on the output.  This regulator along with the appropriate
> transorbs should work well.
>
> Dave Mumert
>
> ------------------------------
>
> Date: Mon, 10 Sep 2001 11:30:49 -0700
> From: "Darrell N." <darrelln at datalog.ab.ca>
> Subject: Re: wb lcd display
>
> Bill Shaw wrote:
>
> > While waiting for my DIY-WB I started thinking about a
> > display for it.
> > I need help in a few areas:
> >
> > 1)  I need someone(s) to review the schematics for technical
> > correctness before it goes to layout.
>
> Can't help you there.  It looks OK to me, but I'm not that familiar with
> either PICs or the display you are using.
>
> > 2)  I need a robust 12V to 5V power supply for it.
>
> Use a National LM2931 or similar regulator, it is designed for automotive
> applications and can handle load dump, reverse polarity, short circuits,
> just about everything you can throw at it.  Get rid of your ferrite beads
> and put in few hundred uH power inductor in series with the input.  A
> couple of honkin caps and possibly a MOV or Tranzorb across the input
> and you should have it handled.
>
> > 3)  I need someone to do the PCB layout.
>
> That I may be able to handle, if there's demand for the display board on
> the list.
>
> > Yell if you can't print the EPS file and I'll see if I can
> > get it to you in another format.
>
> My Adobe Acrobat converted this file into a PDF.  Let me know if you
> want me to upload the PDF to incoming.
>
> darrell n
> Calgary, Alberta, Canada
>

> ------------------------------
>
> Date: Mon, 10 Sep 2001 12:20:43 -0600
> From: "Dave Mumert" <dmumert at telusplanet.net>
> Subject: Re: wb lcd display, PCB software
>
> Hi Darrell
>
> Another Calgarian! small world.
>
> I have been using a small schematic capture/PCB editor program called QCAD.
> It is OK for small projects.
> Check at http://www.winqcad.com/
>
> It is just $99 for 600 pins.  The latest version has copper pour.  The
> autorouter seems to complete most jobs.
>
> Dave Mumert
> Calgary,AB
>
>
> Date: Mon, 10 Sep 2001 12:43:26 -0600
> From: Marc Piccioni <piccioni at cadvision.com>
> Subject: Re: wb lcd display
>
> Bill,
>
> If you can save the file as a dxf or orcad file I can review it and/or
> either make any corrections required/send the corrections back to you.
>
> Do you have the power budget calculated?
>
> /Marc
>

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