A few people in the past have made RFID sensors for the NXT. At last, there’s an “official” third party product for those of less technical capabilities… LEGO has announced yesturday an official partnership with Codatex producing the NXT RFID Sensor seen in the above image. Some technical features frm Codatex website:

- Reads 125 kHZ transponders of type EM4102
- 5 bytes number, i.e. 240 combinations (i.e. 1.099.511.627.775 numbers)
- The reader has three modes of reading: Single read, Continuous read, Stop
- Reading distance up to 3 cm depending on transponder size and orientation
- Transparent front cap with LED signal at detection of a transponder
- Auto power off for saving battery power
- Firmware upgrade feature for future enhancements (saving hardware cost)

I’ve had a prototype of this sensor for some time, and it work very nicely - provided you place it close enough to the RFID tag and at the correct angle (RFID uses radio frequency, and the antenna has well defined spatial response). The package would contain a sensor and two tags, with holes matching Technic pegs. More details are found here.

Guy Ziv