Building a 'unlocker' for the PC using cardreader.

Forum 2005-2010 (read only) Hardware Interfacing
1

Hello.

I recently bought this cheap magnetic card reader:

What i try to do is to connect this device to an Arduino Duemilanove to build a lock for my encrypted partitions on my Linux-PC. I would like to program the Arduino the way he simply "pipes" the data coming from the cardreader to the PC over it's serial line. A daemon running on the PC watches for data coming from the virtual serial port created by the Arduino. The card contains the encrypted key for the partition, the daemon encrypts the key and uses it to mount the encrypted partition on the harddisk.

As a very beginner, my problem is that i know how to communicate with i2c or serial devices, but not with that kind of device. The reader uses 5V-CMOS-level-TTL signals to send data. How would anyone connect this to a Arduino and maybe translate it into 'software bits'? Sampling of the data thru the analogue inputs or is it possible to directly read bits using a digital input?

I also found a detailed specification sheet of this cardreader which explains the I/O signals of the device.
http://rapidshare.com/files/365390999/ZU-M1363S1.pdf.html (1.6 MB)

Has anyone a idea where i could start? :-?

With best regards,
wilbert.

2

A mag stripe reader produces a very similar signal to a wegand RFID reader. This project shows how to interface three readers to an arduino:-
http://www.thebox.myzen.co.uk/Hardware/Crazy_People.html

What you have to do is to change things so the clock data only is triggering the interrupt and read the data line in the interrupt service routine.

3

Thank you for your quick response.

Yes, that project looks very similar. That gives me a good starting point to begin with. I think you saved a rainy weekend with your tip.

Wilbert :slight_smile:

4