ATQA (Answer To reQuest code A) is a two-byte code in Near Field Communication (NFC) technology that is used to identify the type of RFID tag or device that is communicating with the NFC reader. When an NFC reader sends out a signal to communicate with a nearby tag or device, the tag or device responds with its ATQA code to indicate its presence and capabilities.
The ATQA code contains information about the type of tag or device, such as its manufacturer, memory capacity, and communication protocol. It helps the NFC reader to determine how to communicate with the tag or device and what type of data can be exchanged between them. The ATQA code is the first piece of information that is exchanged during the NFC communication process and is used to establish a connection between the reader and the tag or device.
