AN3985 datasheet(89/105 Pages) STMICROELECTRONICS

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AN3985

Application example

Doc ID 022255 Rev 2

89/105

Figure 5 details these different steps.

Figure 5.

Test config procedure flowchart

8.1.4

ISO/IEC 15693 Protocol selection

Before beginning to communicate with a contactless tag, the RF protocol and its parameters

should be set. This step ensures that it is done before entering the main loop.

8.1.5

Tag hunting

The Tag Hunting function sends an inventory and a Get system Info command. The

contactless tag responses are stored into the MyTag15693 structure.

The inventory sent is an inventory 16 slots, therefore if several contactless tags answer the

command, then only one UID will be retrieved or potentially 16 structures will be needed.

The solution proposed and used in the inventory 16 slots is to store the UIDs retrieved into

the internal EEPROM of the STM8L. When the inventory is finished, the number of

contactless tags seen is available thanks to the

ISO15693_Inventory_16slots_Nb_UID_Retrieved variable.

Commands may be addressed to each tag seen individually. The procedure is exposed

using the Get System Info Command. If only one tag answers the inventory, its UID is stored

in the STM8L EEPROM, and on top of that the UID is written in the Tag structure.

MS19964V1

Start of Wait for interrupt mode

End of Wait for interrupt mode

Wake Up STM8L

STM8L timeout

= 5s ?

Yes

CR95HF Detect

a tag ?

Yes

Test communication

Ok ?

Yes

Wake Up CR95HF

Wake Up STM8L

Put to sleep CR95HF

AN3985 Datasheet(PDF) 89 Page - STMicroelectronics