View Full Version : Question about parallax RFID reader

08-03-2008, 11:57 PM

I have a question, when the RFID reader scans a tag it sends on its serial output port 11 bytes, with start bit being 0A and the remaining being for the tag's ID
My question is, if the tag ID is only 40 bits long (5 bytes), why does the RFID reader send 10 bytes?

Also, I was looking at the BASIC stamp code for integration with the RFID reader, the tags are stored hexadecimal values that equal to 5 bytes only, and yet they are being compared to 10 bytes..

Can someone please help me understand how this happens?

Mike Green
08-04-2008, 12:10 AM
The tag is sent in human readable form with a Line Feed character first, then ten hexadecimal digits, then a Carriage Return which is actually 12 characters. When the Stamp reads this, it waits for the leading $0A, then uses the HEX2 formatter (look in the manual) to convert each pair of characters to an 8-bit byte, then the $0D acts as a terminating character.