Memory size limitation:
Type 1: up to 1KB
Type 2: up to 2KB
Type 3: up to 1MB
Type 4: up to 64K
Data Rate limitation：
The max communication speed is 424 Kbps, is lower than Bluetooth.
When your phone scans the tag, you have to make your phone unlock.
How to read / write:
Please refer to: http://developer.android.com/guide/topics/connectivity/nfc/advanced-nfc.html#read-write
To be simple:
Tech tech = Tech.get(Tag); tech.connect(); tech.transceive(byte); tech.close();
Tech tech = Tech.get(Tag); tech.connect(); byte data = tech.readValue(); tech.close();