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Hi everyone. I am sure somebody here will have the answer. I am attempting my first (complicated??) design and hope you guys can help. For the first part, I am considering using a 4x3 matrixed numerical keypad for up to 4 (6, preferably) users to enter their own secret PIN. Once set, each user can input their PIN to activate a logic 1. There needs to be a separate logic 1 output for each user.

I have come up with a design that does part of this. The user's PIN is selected in 4 bit binary by DIP switches (it's ok if the "master" user knows the PIN of the others). When the PIN is entered, logic gates determine if the PIN input matches that set by the DIP switches and allows a logic 1 to be output, otherwise logic 0 is retained. This is fine for just one user, but how do I adapt for multiple users? Or perhaps there is an easier way.

I'd also like to include a LCD to make the system user friendly. In fact, I already have the display module. It's "Reflective LCD display,162D-BA-BC". It can be found on the RS website; stock number

532-6470. A pdf data sheet is also available here. Please bear in mind that I need to utilise the display for other things too such as time of day and also as a countdown timer for each user.

This is just one section of the overall project.

I prefer to keep the component count to a minimum, but also need to use readily available parts.

I am considering the use of PIC chips, but have to admit my knowledge of them is very limited.

If anyone can help, I am happy to answer any questions you may have to the best of my ability.

Regards, Colin (yes, another one)

Reply to
Colin
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The way I'd do this would be to use a PIC with flash, and have it remember the PINs. I'd set up the "master" user with a way to access the thing to enter PINs (and delete them). Basically, if you're spending the $$ on a microprocessor, you want to make it do all the work you can.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Posting from Google?  See http://cfaj.freeshell.org/google/

"Applied Control Theory for Embedded Systems" came out in April.
See details at http://www.wescottdesign.com/actfes/actfes.html
Reply to
Tim Wescott

Yes, a much better approach than a bushel full of capacitors, relays, and thyratron tubes!

Luhan ;)

Reply to
Luhan

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Reply to
Homer J Simpson

Reply to
Colin

Reply to
Colin

ISTR there's a PIC emulator out there for download. Quicker and easier to learn on.

Reply to
Homer J Simpson

A kit is a good starting point - it can lead to ideas you can use.

Reply to
Homer J Simpson

Reply to
Colin

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might be worth a browse.

Reply to
Homer J Simpson

I'm in the final stages of the schematic (It'll get done in PCB next) of a PIC prototyping system based on the 16F877A (or soon the 16F887). It's a complimentary kit for my Inchworm ICD2 clone kit.

See the updates section for a schematic. (Low res at the moment but that will change) It's 4x3 + 1 keypad & 2x16 backlit LCD display would allow you to write code (programming AND debugging via Inchworm and MPLAB)

You could also use the demo version of PICBASIC Pro which works in demo mode on the 16F877A and supports MPLAB and the Inchworm.

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Reply to
William at MyBlueRoom

Opps

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Reply to
William at MyBlueRoom

X-Face: ?)Aw4rXwN5u0~$nqKj`xPz>xHCwgi^q+^?Ri*+R(&uv2=E1Q0Zk(>h!~o2ID@6{uf8s;a+M[5[U[QT7xFN%^gR"=tuJw%TXXR'Fp~W;(T"1(739R%m0Yyyv*gkGoPA.$b,D.w:z+ I agree with you guys, I just wish I knew how to incorporate a PIC into the

for a low speed design like this (100ms response time would be plenty) you start by dreaming up whay your "dream chip" would be like (inputs and outputs needed to work your hardware) then you pick a microcontoller with enough of each and enough internals stuff to do the task.

and then you start coding to turn the micro into youe dream chip.

There are microcintrollers that can be programmed in basic.

--

Bye.
   Jasen
Reply to
jasen

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starting

can

BASIC,

Reply to
Colin

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