AS3955 datasheet(67/111 Pages) AMSCO

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ams Datasheet

Page 67

[v1-01] 2015-Apr-29

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AS3955 − Detailed Description

Reading Data from Addressable Registers (Register Read

Mode)

After the I²C slave address, the address of register to be read

shall be provided, MSB first. Then one or more data bytes are

transferred to SDA output, also MSB first. As in case of the write

mode, also read mode supports auto-incrementing address. In

case the register at the defined address does not exist, all 0 data

is sent to SDA. In the following figure, an example for reading

of single byte is given.

Figure 73:

Reading a Single Register over I²C

Writing and Reading EEPROM through I²C

EEPROM data can be read and written through I²C interface. Due

to possible conflict with RFID interface, additional arbitration

bit can be set (IC_CFG0) in order to set the priority access to the

EEPROM access. If EEPROM write operation is terminated due

to higher priority of the RF an I_spi (Interrupt Register 1), an IRQ

is sent.

Block Address Byte

Both EEPROM Read and Write use Block Address byte to define

the EEPROM block address to be accessed. Seven MSB bits of

the Address Byte are used to define the address; while the last

bit is don’t-care (it is used to synchronize EEPROM access).

Figure 74:

EEPROM Block Address Byte over I²C

EEPROM Block Address

WA6

WA5

WA4

WA3

WA2

WA1

WA0

Slave address

Mode Byte

SCL

SDA

Data

Slave address

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