Interfacing ID-20 with PIC 16F88

I’ve gotten a little confused with this device also.

Re-reading all of your posts I see you have selected the Weigand26 format. I was looking at the Magnetic Emulation format in the last post.

In the Weigand26 format (and Mag. Em.) 4.7k Ohm resistor pull-ups to +5V are require on pins 8 & 9 (I’ll guess these are open collector or open drain outputs).

There is a Data Format Structure for Weigand26 on 4 of the data sheet but I do not understand it or Data0 & Data1. Yet. so off to google…

Did find this on Weigand26 :

http://www.edaboard.com/ftopic104482.html

http://www.hidglobal.com/documents/unde … _wp_en.pdf

http://en.wikipedia.org/wiki/Wiegand_interface

Finally an explanation of Data0 & Data1. The Wiki article does explain them well enough.

This one: http://www.ibtechnology.co.uk/pdf/magswipe_dec.PDF

has a bit more detail including a timing diagram and a few of the other links on the Wiki page have more than enough info to use decode the Wiegand 26-bit format.

These are basically differential signals at TTL levels so they connect directly to input pins on a 5V PIC.

The PIC code just needs to read these inputs and decode the Data0 & Data1 into logic highs or lows.