Iso14b command group

This command group implements the low-level ISO 14443-3 (Type B) commands according to the ISO 14443-3 (Type B) standard

A PICC compliant to ISO 14443-3 (Type B) is always in one of five states:

1. Power off state
2. Idle state
3. Ready state
4. Active state
5. Halt state

As long as the PICC is not present in the HF field of an antenna, it is in power off state. When the PICC gets into the HF field, it will switch to idle state automatically. The Iso14b.Request command scans for PICCs in idle state and returns necessary information about them to the host. Furthermore, this command will change the state of the detected PICCs to ready state. The Iso14b.Halt command can be used to set PICCs from ready state to halt state so that they do not respond to conventional Iso14b.Request commands any longer. PICCs in halt state can only be reactivated by setting a special parameter flag in the Iso14b.Request command.

From ready state, one or more PICCs may be switched to the active state via the Iso14b.Attrib command. Not all PICCs support being in active state while other PICCs are at the same time: such PICCs need to be selected exclusively instead.

Communication with the PICC by means of APDU exchanges is subject to the ISO 14443-4 standard which is explained in detail in the Iso14L4 command group documentation. Only PICCs in active state are able to execute ISO 14443-4 commands. For proprietary PICCs which are not compliant to the ISO 14443-4 standard, Iso14b.TransparentCmd should be used instead. It provides a raw communication channel between the application and the PICC, without any interpretation of the transferred data within the reader, thereby allowing to send/receive arbitrary request/response data to/from the PICC.

After data exchange is completed, the PICC may automatically be switched to halt state so that it does not respond to any command which may follow. Depending on the PICC being compliant to the ISO 14443-4 standard or not, either a special command of the Iso14L4 command group or a proprietary card command transmitted via Iso14b.TransparentCmd have to be used for this purpose. PICCs in halt state can only be reactivated by setting as special parameter flag in the Iso14b.Request command.