Just as I get the prototype working, we have decided to move from the 125khz EM4100 RFID to the 13.7Mhz Mitac RFID standard. the reason is two fold

1. We wanted to simplify configuration and improve security by having the SSID, password and host in the tag as opposed to three different bar-codes and also have part of the encryption key in the RFID tag. That means one swipe of the tag can configure the terminal. The RFID tags have 700bytes of storage will be secret sauce though)
2. The main client is moving to this standard and away from EM4100

There is actually a plus to this in that you can get per-assembled RFID readers for about $3 (I actually just bought 50 RC522 readers off aliexpress for $132 including delivery - how do they even do that!) the new readers are SPI bus and there are loads of libraries already available in the Arduino community.

5 of the new PCB's are being made and hand assembled at smart-prototyping at a cost of $40 each should have them returned in a week or two.

I have also ordered some filter glass as opposed to the plain glass, this should improve the performance of the bar-code reader and block out the inside PCB to pesky users, should also make it all look a bit more professional.

All the changes will require a fairly big re-write so while I am about it I am also going to try and get the USB boot-loader working, there is code for the AVR dude programmer and PIC32/Chipkit system which I am hoping to be able to modify.

This is my busiest time of the year supporting several wineries during their vintage, it is now coming to an end and should give the time I need to finish everything.

Note the PCB and schematic have been updated to this new version of RFID, the previous version is still available if you search my projects on EasyEDA