Software description

AN3255

16/24

Doc ID 17784 Rev 1

3.3

Application principle

This application initiates communications with the tags present in the range of the

electromagnetic field generated by the reader antenna, and read the tag UIDs. If the

operation succeeds, the STM8S105C6T6 emits a beep and blinks LD1.

When running the code in debug mode from STVD development tool, the UID value can be

displayed in the Watch windows.

board, and to transmit/receive frames to/from the tags (see Table 6). Communications with

the tags are managed by the state transition diagram shown in Figure 3.

A possible way to improve this application would be to use an LCD screen to display the tag

unique identifier (UID). Another improvement could be to implement the CR14 anti-collision

capability which allows the reader to select up to 16 tags (one at a time) during predefined

time slots.

Refer to Figure 5 for the flowchart of the application software main loop.

Table 6.

TAG commands used within this application

Tag commands

Description

Initiate()

To detect if a tag in Ready state is present in the reader field range

Select(Chip_ID)

Allow the tag to enter the Selected state

Get_UID()

On receiving this command, the tag returns its 8 UID bytes