AS3955 datasheet(26/111 Pages) AMSCO

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[v1-01] 2015-Apr-29

AS3955 − Detailed Description

Memory Organization

AS3955 contains an embedded EEPROM module which can be

accessed via RF or SPI / I²C interface. EEPROM contains 4096 bits

(512 bytes) organized in 128 blocks of 4 bytes each. Blocks in

EEPROM are numbered from 00h to 7Fh. Bits in a block are

numbered from 0 to 31.

Most of the EEPROM is NFC Type 2 Tag user data area (472 bytes).

The position of the dynamic lock bits is fixed at the end of NFC

Type 2 Tag user data area (blocks 7Ah and 7Bh). The

configuration bits which define AS3955 operating options are

stored in blocks 01h, 7Ch, 7Dh, 7Eh, 7Fh. Housekeeping

information is stored in block 00h. 4kbit EEPROM organization

is shown in Figure 27.

AS3955 is also available in 2kbit version. In this case the data

area is reduced to 216 byte. AS3955 internal user memory

implements static and dynamic lock bits according to NFC

Forum Type 2 Tag standard. Configuration and lock bits, as well

as the full 2kbit EEPROM organization, are shown in Figure 28.

4kbit EEPROM Organization

Numbers of dynamic lock bits:

• Data area size in bytes:

4*(127 – 3) – 7 – 17 = 472 bytes

• Number of dynamic lock bits:

(472 – 48) / 8 = 53 bits (53 bits)

AS3955 データシート(PDF) 26 Page - ams AG