AN3985 datasheet(90/105 Pages) STMICROELECTRONICS

90 / 105 page

Application example

AN3985

90/105

Doc ID 022255 Rev 2

For one slot inventory, only UID can be retrieved or there will be a collision. To prevent a

collision (with 1 or 16 slots), a mask can be added to the inventory command. The mask

corresponds to the LSB bits of the UID, the contactless tag compares those with its UID and

answers only if they match. The length of the mask is in bits, unused bits in the byte must be

reset in order to transmit whole bytes.

8.1.6

Display

If the inventory and Get System Info commands passed, then the UID and the ICRef of the

tag are displayed. Note that as the MSB byte is common to all contactless tags, it is not

displayed.

For STMicroelectronics manufactured contactless tags, a database containing the ICref is

present in the miscellaneous files.

8.1.7

User application

User application is based on the utilization of the joystick present on the STM8L 1528-Eval

board. This enables the user to perform the actions described in Figure 6:

Figure 6.

Joystick utilization

A detection of a contactless tag or pressing the Reset button can exit this mode.

8.1.8

Low power modes

The CR95HF embeds a low power state named "tag detector state". In this state, the

CR95HF device is turned in Idle state and will periodically check if a tag is present in the

volume operation. If a tag is detected, the CR95HF devices will wake-up.

The STM8L integrates different low power modes. Once STM8L is turned in low power

mode, it can be waken up by itself using an internal timer or by an external interruption.

MS19962V1

Joystick

Left State :

A calibration of the tag detector

is launched.

Then a test is done in cleared

field.

This procedure has a duration of

around 6 seconds during while

the CR95HF is in Idle State and

looks for contactless tag.

The STM8L displays the number

of seconds remaining with dots.

Right State :

Low power mode.

When pressed, the STM8L and

the CR95HF turn into one of

three low power modes

described below. (1)

Up state :

An IDN command is sent to the

CR95HF and its response is

displayed on LCD.

Down State :

RF Field is alternatively turned

on and turned off.

AN3985 数据表(PDF) 90 Page - STMicroelectronics

AN3985 数据表(HTML) 90 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

数据表下载