Tutorial: Adding an ISO 7816 card reader to your Linksys WRT54G

This project is for people who would like to add an ISO 7816 card reader to their Linksys WRT based router. We will connect it to one of the serial ports and use the DMZ GPIO to reset the card.

Pictures

• The insides of the router
• The finished product with card reader installed

What you need

• A soldering iron and a bit of tin solder (and a little bit of soldering skills)
• An ISO 7816 card reader, 74LS07 and an oscillator at 3.57 MHz (or any other speed you would like)
• Some pieces of thin wire
• Optionally a breadboard for easier mounting
• A Linksys WRT54G (hardware version 2 - others should also work)

How to proceed

1. The following is a diagram of what we are trying to put together:

                        +3.3V (VCC)
                           o
                           /
                           \ 22K
                           /
                           \
                           |
   RxD o-------------------+--------------------------o I/O
                      |\   |
   TxD o--------------| |--+
                     1|/ 2
                     74LS07
   
                     pin 7=GND, pin 14=VCC
   
   
   
   DMZ o----------------------------------------------o RST
   
        1M         2.2k        3|\4
     +-/\/\/--+----/\/\/-----+--| o-----+-------------o CLK
     |        |2             |  |/      |
     |       -o-             |          |100 pF
     |     /_____\           |         ===
     |        |1             |          |
     |        | 3.579545 MHz |          |
     |        |     +--+     |          -      74HC04
     +--------+---| |  | |---+         GND     pin 5,7,9,11,13=GND,
              |     +--+     |                 pin 14=VCC=+3.3 V
              |27pF          |27pF
             ===            ===
              |              |
              -              -
             GND            GND
   

   RxD and TxD is the serial port inside the router. Actually you have 2 serial ports to choose from and the link will also tell you where to find 3.3V. DMZ is the LED on the front of the router. The oscillator design is of course just a suggestion. If you want to make it easy just buy a ready-made oscillator instead.
2. Proceed by soldering wires to RxD, TxD, 3.3V, GND and DMZ inside the router.
3. Now put together a little breadboard with the card reader, the 74LS07 and your oscillator of choice and connect them as described in the diagram. Pay special attention to how you choose to mount the reader on the breadboard as you will try to fit it nicely inside the router when done.
4. If you can't remember the pin-out of your card reader here is a little help depicting the card which goes inside it:

              ______________________________________
   	 /                                        \
   	|                                          |
   	|                                          |
   	|    C1   C5                               |
   	|    C2   C6                               |
   	|    C3   C7                               |
   	|    C4   C8                               |
   	|                                          |
   	|                                          |
   	|                                          |
   	 \________________________________________/
   
   
   
   	C1	VCC	Supply voltage
   	C2	RST	Reset signal
   	C3	CLK	Clock signal
   	C4	-	reserved
   	C5	GND	Ground
   	C6	VPP	Programming voltage (5-25 V)
   	C7	I/O	Data input/output
   	C8	-	reserved
   

5. Mount the card reader somewhere inside your router. If you are a bit clever you can actually make it fit nicely at the side of the router in the top.
6. That was easy. We are now ready for the software part.

Software

The software part is actually pretty easy since tools have already been written for you. The NewCS software package comes bundled with a pre-compiled OpenWRT MIPS version, which I suggest you use. This of course means that your life will be a lot easier if you choose OpenWRT as your firmware on the router.

With OpenWRT installed you still need some packages installed to get NewCS running. At the moment they can be found at http://downloads.openwrt.org/whiterussian/packages/. You will be needing libgcc, libopenssl, libpthread and kmod-diag.

That's it!