View Full Version : Parallax RFID reader / Serial Communication

03-20-2007, 12:00 PM
Hi all!
I'm working on a school project that makes use of Parallax's RFID reader. I am trying to receive the ID from one of the compatible tags sold by Parallax, however, I am having no luck. I have connected the RFID reader to a PC using a serial cable and viewing the reader's output using Hyper Terminal, but the output is seemingly all garbage ASCII characters with no discernable pattern. The RFID tag should output a 12 byte code in hex.

The documentation for the RFID reader says the following:

The Parallax RFID Reader Module can connect directly to any TTL-compatible UART or to
an RS232-compatible interface by using an external level shifter.

I am unfamiliar with serial communication standards. I do not know what an 'external shifter' is, and have no luck Googling such a device.

Also, this RFID reader will eventually be connected to a PIC 16f877a which supports UART, but I need to do more research on that issue.

So can anyone please explain how I would be able to obtain the ID code from the tag and reader using a PC, please? I've wasted a number of hours trying to do this already.


03-20-2007, 12:13 PM
This exact topic came up in the Basic Stamp forum last week: http://forums.parallax.com/showthread.php?p=638204 . Schematics of possible level shifters are posted at the end of the thread.

03-20-2007, 12:25 PM
Thanks, I think this will be very helpful.