How to fix uid in NFC
I want to fix the uid for nexus s and use the phone to mark on the NFC screen. The shield will show the ID. But when it flows to the nfc screen, the id doesn't match. Can I correct my uid?
Most likely it is NFCID: NFC peer-to-peer identifier. This ID is randomly generated anew by the NFC equipment on every NFC connection and cannot be corrected.
The current SDK does not allow card emulation, so you cannot use the phone as a tag.
Since the ID changes peer-to-peer for each connection, you will need to define an NDEF entry with a text value. Make this a fixed ID. On the other hand, on the shield, you will need to read this entry to find the fixed value / ID.
https://github.com/adafruit/Adafruit_NFCShield_I2C/tree/master/examples contains some examples of how to manage NDEF records, but only on the classic MiFare. If you are using Ultralights or other tags, this will be different.