Prevent Multiple Reads

Splinky

Hi,

I purchased a 28340 USB rfid reader that is to be used on a door access system. I have a purchased software package that monitors a com port for a tag to be scanned, compares it to the database and sends a signal out of another com port if its ok to open the door. We were using a barcode reader but some people seemed to have a lot of issues swiping a card so we wanted to try the rfid key fobs.

The problem I am having is that the reader spits out the tag ID repeatedly which either unlocks the door multiple times or else messes up the software by providing too long of a tag ID. Is there any way to set the rfid reader to only transmit one tag ID and then delay before processing another?

Thanks in advance for any guidance on this.

Mike Green

No.

The RFID reader is designed to continuously (repeatedly) read an RFID tag until the tag is removed from within range or the DTR signal is turned off (on the USB serial port). The only way to do what you want is to interpose some kind of hardware or software editor between the RFID reader and your purchased software package. Doing this using software requires some sophisticated PC programming on your part. Essentially you need to write a serial I/O driver that receives the repeated RFID packets, passes on the first packet to another "virtual" com port, and discards any subsequent equal packets. In hardware, it's much much easier if you have a serial RFID reader. You could use a Propeller to read the RFID packets over a serial port, again discard any duplicates, and send the edited stream to the PC program over the same USB serial port used for downloading new programs to the Propeller.

Chris Savage

The example software we have available for the RFID Reader USB disables the DTR line for a preset period of time as soon as it gets a valid read. This also has the effect of making the LED turn green to indicate that the read was good before going active and making the LED red again.