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card reader, retrieving memory without using MP.

S

Stuart

Jan 1, 1970
0
I'm basically trying to make a CHEAP card reader. Basically I want a
way to read ID off a card. Now I can use some meory chips and give a
card an ID but then I'd have to provide it clock cycles to retrieve
that ID i.e. using a microprocessor (clearly avoidable). I ain't no
pro and am in fact looking forward to learning all this. Since I
encountered a dead end here. I came up with real primitive Ideas. now
this card reader doesn't have to be optical or contact less, in fact i
could do with a slot in which user could put in the card be verified
and then take the card out. So this real primitive idea is that I put
high resistance for a 0 and low resistance for a 1. then apply voltage
at every one of those points. correspondignly getting a zero or 1 as
has been assigned to that user. a port would then be able to read
these values and thus give the system an id to be verified. problem
with this is clumsy design and the construction of the card (not to
forget the card's size). If perhaps there was a way to read the data
stored in a memory chip and pass it like a bit stream in shift
registers and these could be connected to the serial ports of the
computer. Please gimme some insight into this and links could be great
help. Please, if it's possible mail me at [email protected] or
[email protected]. Thanx!

Stuart
 
C

CWatters

Jan 1, 1970
0
Microprocessors can be cheap. In 1000 off quantities you can buy them with
flash memory for <$USD 2 or OTP <$USD 1 and ROM versions in volume will be
even less.

What level of security is required? eg Does it matter if it is easy to copy
an ID card?
 
S

Stuart

Jan 1, 1970
0
Security is not that big an issue here. This card access facility is
being installed just to have an idea of 'who came in today?' an end of
the day analysis. Also where this facility is being provided it seems
unlikely for anybody to know anything about electronics so no security
(tho there's isn't much to worry about anyway) breaches expected that
way. Mr. Watters could you give me any references to articles where I
may find info about creating cards using MPs and ROMs.

Thanx

Stuart
 
M

Mjolinor

Jan 1, 1970
0
Stuart said:
Security is not that big an issue here. This card access facility is
being installed just to have an idea of 'who came in today?' an end of
the day analysis. Also where this facility is being provided it seems
unlikely for anybody to know anything about electronics so no security
(tho there's isn't much to worry about anyway) breaches expected that
way. Mr. Watters could you give me any references to articles where I
may find info about creating cards using MPs and ROMs.

Not entirely clear on what you want to do but it seems to me that a "gold
card" is what you want, that's a PIC16F84 and 24C16 in a wafer, they are
about £2 each in 1s, very cheap in 50s or so. Very easy to programme and
read using a PC and about $20 wortrh of hardware that you can buy or make.

If you search for gold wafer on google or browse a few satellite TV sites
you will find them. If you want more security or more capability then there
are Atmel micro based cards for not a lot more money.

Even from scratch without a PC the technical requirements in terms of clock
and serial transfer are really simple.
 
C

CWatters

Jan 1, 1970
0
There is loads of stuff on the web. Try this page for some S/W.

http://www.maxking.co.uk/smartcardsoftware.htm

I've no experience with these programs but these look like they might be of
interest....

"Smartclock, A smartcard clocking in system. Control employee arival and
departure times."
"smartlock, program to control unlocking of doors etc.

Going slightly off topic...

Some time ago the Olivetti Research lab in Cambridge England (now owned by
AT&T) developed an IR Active Badge system that also did something like you
propose. I'm not sure if it's available commercially and the badges wern't
cheap back in the early 1990's. This system allowed you to find out where
people were in a large building for example.
http://www.uk.research.att.com/ab.html

Why would people wear an active badge....
http://www1.cs.columbia.edu/graphics/courses/mobwear/resources/harper-xerox93.pdf
 
W

Wim Lewis

Jan 1, 1970
0
I'm basically trying to make a CHEAP card reader. Basically I want a
way to read ID off a card. [...]

It's not clear to me whether you have some existing cards in mind which
you want to be able to read, or whenther you're free to choose any
card+reader technology you like. If the latter, have you thought about
a simple barcode or magnetic stripe? As the user swipes a card past
the reader, the barcode or stripe will naturally produce a serial bitstream.
The difficulty with this approach is timing: people will swipe their
cards at different rates, and the rate won't be constant (they might start
slow and speed up, for example). There are various way to deal with
that, such as having a synchronization preamble, or a "self-clocking"
data format, or just having two stripes on the card (one for clock and
one for data). You usually end up having to have a microcontroller
in the reader to handle the timing.
forget the card's size). If perhaps there was a way to read the data
stored in a memory chip and pass it like a bit stream in shift
registers and these could be connected to the serial ports of the
computer.

Existing "chip cards" work like this. You could get similar functionality
by putting a cheap 2-wire EEPROM on the card. Actually, I suspect that
you can buy unprogrammed chipcards pretty cheaply.

But if you are going to make, (say) 5 readers and 100 cards, then it's
worth making the reader more complicated/expensive if you can make the
card cheaper.
 
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