Magstripe interface - multiple serial datastreams

Archiver

Hello everyone,

I'm trying to interface with a magnetic card reader that would require me to
read
three seperate inputs at the same time. I'm fairly new with the stamp, and I'm
learning on a Stamp 2sx.

There are seperate clock and data lines for tracks 1 2 and 3 for a total of six
lines. They are clocked seperately because there are different data densities on

each stripe, and the data rate is dependent on the rate at which the user is
inserting or withdrawing the card.

I know it is trivial to read the data from one particular stripe (data/clock
pair) at a
time with SHIFTIN, but the problem is the data is coming from three sources at
once at different clock rates. Am I up a creek without a paddle? Is there some
trivially easy way to do this short of having the user swipe the card three
times?

Thanks in advance for any help,

John Laur

Archiver

Not knowing how much data is on each line, I would use a shift
register for each line they would fill up and you would shift
them back out to your sx one at a time.

---

Original Message

---

From: "gorkish" <gorkish@h...>
To: <basicstamps@yahoogroups.com>
Sent: May 16, 2002 12:07 PM
Subject: [noparse][[/noparse]basicstamps] Magstripe interface - multiple serial
datastreams


Hello everyone,

I'm trying to interface with a magnetic card reader that would
require me to read
three seperate inputs at the same time. I'm fairly new with the
stamp, and I'm
learning on a Stamp 2sx.

There are seperate clock and data lines for tracks 1 2 and 3 for
a total of six
lines. They are clocked seperately because there are different
data densities on
each stripe, and the data rate is dependent on the rate at which
the user is
inserting or withdrawing the card.

I know it is trivial to read the data from one particular stripe
(data/clock pair) at a
time with SHIFTIN, but the problem is the data is coming from
three sources at
once at different clock rates. Am I up a creek without a paddle?
Is there some
trivially easy way to do this short of having the user swipe the
card three times?

Thanks in advance for any help,

John Laur


To UNSUBSCRIBE, just send mail to:
basicstamps-unsubscribe@yahoogroups.com
from the same email address that you subscribed. Text in the
Subject and Body of the message will be ignored.


Your use of Yahoo! Groups is subject to
http://docs.yahoo.com/info/terms/

Archiver

Thanks, Larry for the suggestion.

ISO7811 standard provides the following:

Track 1: 210 bits/in for 79 6 bit read-only characters
Track 2: 75 bits/in for 40 4 bit characters
Track 3: 210 bits/in for 107 4 bit characters

Inhumanly fast (50 in/s) swiping should yield a data rate of no more
than 10,000bps or so: the problem is that the stamp hasn't the
interrupts,
though I think the 2sx may be fast enough to simply "poll" the clock
lines in
a tight loop while stacking the bits up in some variables. Is this
totally
infeasable? Programming a pic to cache the read and spit it out
serially when
complete probably wouldn't be that hard, but I don't have the
equipment...

Can you elaborate a little more on the shift register solution -
perhaps you have
seen a project using something like this? I am still pretty green
when it comes
to microcontrollers.

John

--- In basicstamps@y..., "Larry Gaminde" <lgaminde@t...> wrote:
> Not knowing how much data is on each line, I would use a shift
> register for each line they would fill up and you would shift
> them back out to your sx one at a time.
>
>

---

Original Message

---

> From: "gorkish" <gorkish@h...>
> To: <basicstamps@y...>
> Sent: May 16, 2002 12:07 PM
> Subject: [noparse][[/noparse]basicstamps] Magstripe interface - multiple serial
> datastreams
>
>
> Hello everyone,
>
> I'm trying to interface with a magnetic card reader that would
> require me to read
> three seperate inputs at the same time. I'm fairly new with the
> stamp, and I'm
> learning on a Stamp 2sx.
>
> There are seperate clock and data lines for tracks 1 2 and 3 for
> a total of six
> lines. They are clocked seperately because there are different
> data densities on
> each stripe, and the data rate is dependent on the rate at which
> the user is
> inserting or withdrawing the card.
>
> I know it is trivial to read the data from one particular stripe
> (data/clock pair) at a
> time with SHIFTIN, but the problem is the data is coming from
> three sources at
> once at different clock rates. Am I up a creek without a paddle?
> Is there some
> trivially easy way to do this short of having the user swipe the
> card three times?
>
> Thanks in advance for any help,
>
> John Laur
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@y...
> from the same email address that you subscribed. Text in the
> Subject and Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/