Proximity Reader Help

Guest · Posted: Fri Jun 25, 2004 7:55 pm

Hello,

I have an application that will use an RFid proximity reader but my concern is? the output of the reader is a Weigand26 standard with two output Data0 and Data1.

How can I convert the weigand26 to RS232 signal such that I can receive the data at the PC Host?

Any information that can help or maybe a sample snippet or driver that will convert weigand26 to RS232.

Thank u.

Ritchie

chingB · Joined: 29 Dec 2003 Posts: 81

I need also this information..

thnx

rwyoung · Joined: 12 Nov 2003 Posts: 563 Location: Lawrence, KS USA

What I understand about Weigand is that it is a data packet of 26 bits where the ones are represented by a pulse on the Data1 line and the zeros by a pulse on the Data0 line. There is no clock or baud rate associated as it originally came "directly" from the read head of a mag-stripe reader.

Googling around I found a brief description of the bits:
http://www.control.com/1026171143/index_html

One thing to note is the communication is unidirectional so you can't send anything from the PIC back to the RFid reader through those lines.

If I was going to do this I'd use two pins on Port B that can generate the "interrupt" on change event and use that to build up my 26 bit packet. I'd also use one of the timers to set a maximum timeout so that once a packet starts coming, it has to finish within some reasonable amount of time or the PIC dumps its buffer and begins waiting for the start again.

Then once the 26 bits are present they can be shoved out through the UART to the PC. The PIC could do a little pre-processing before sending them along.
_________________
Rob Young
The Screw-Up Fairy may just visit you but he has crashed on my couch for the last month!

chingB · Joined: 29 Dec 2003 Posts: 81

Anybody in the community have implemented a Wiegand26 to RS232 protocol converter using a PIC microcontroller?

Thanx