[Diy_efi]Re: looking for help with a prom N82S181]

mbelloli at speedymotorsports.com mbelloli at speedymotorsports.com
Fri Nov 12 07:25:30 GMT 2004

>---------------------------- Original Message
---------------------------- >Subject: RE: [Diy_efi] Re: looking for help
with a prom N82S181
>From:    "Steve Ravet" <Steve.Ravet at arm.com>
>Date:    Thu, November 11, 2004 11:16 pm
>To:      "A list for Do-It-Yourself EFI" <diy_efi at diy-efi.org>
> Pin 18 (/CE - chip enable on the 2716) held to 5v - I
> understand that one.
>  And yes it is at 5volts always.  So pull this to ground instead.
> Enabling the chip.
>> Pin 19 (a10 on the 2716) which I was saying was noise - isn't
>> is it?   Now
>> from what Steve was saying, and please correct me if I am
>> wrong, is that only half of the signal is usable?  When at
>> Vcc ok, but when at Gnd I am going to have a problem when
>> hooked to a 2716 eprom.  So only half of the time this signal
>> would be usable.  Is that what was being said?  So this
>> signal is of no use to me with the 2716.  Instead wire it to
>> Vcc, or Gnd depending on which bank I want all my reading to
>> be done from.
>Looks like a clock to me, but I don't know why a clock would be connected
>to a chip enable.
>> Pin 20 (/oe - output enable on the 2716) Pass through
>> unchanged.  Here I have the correct signal to enable the
>> output of data to the bus.  This is my true enable signal.
>> It is good as it stands.  When pulled low, enables the output
>> phase of the 2716.
>> Pin 21 (Vpp - programming power on the 2716)  Shouldn't go to
>> ground, or
>> be toggled on the   2716.  Pull to 5v and that should be all that is
>>necessary at this pin.  We're not programming.

     Ok, tomorrow if I can get the customer to do a drive by, I'll try
putting my chip in again.  And let everyone know what happened.  I'll
also take a pic of the mainboard, and take a look for a 16 pin dip
seeing if it is attached to pin 20.  I've been trying to find some
more information on the net - samples of data line traces for memory
chips.  Anybody have any good ideas?  I really want to get this under
my belt.  Hardware has become my hobby now that I have "Hobby
Engineering" right next door to the shop I work. 
www.hobbyengineering.com I just bought a pic programmer, and a couple
pic chips to play with, and as soon as he gets some of the
protoboards to together I'll be seeing what I can do with pic chips. 
They look like a lot of fun.
     I am thinking of doing a bank switching board so I can change between
a couple different bins on the fly.  Does anybody have any experience
with this?  I have it working to a point right now.  You have to
switch while the power is if, or you'll get a check engine lamp.  I
was hoping if I wrote all the chips based off the same base chip - I
could simply switch between them while driving seemlessly.  The
computer would be unaware of the switch.  If I'm understanding what
I've learned with N82S181, there is time period where the rom is not
active, and it would be during this time that I would switch to a
different bank.  As long as I did it in this time where the rom
wasn't being read I should be ok, right???  I had used a rotary
switch for my first model...and then I read about bounceless
switches.  Oops.  I hadn't thought about the noise a switch produces,
and how that would effect my circuit.  And so, I am now learning the
Pic processor with a bounceless switch routine.  digital controls for
digital circuits.

Thanks everyone for the help you've given.  Hopefully tomorrow I'll be
able to give everyone a thumbs up.


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