ST25R3920 datasheet(52/152 Pages) STMICROELECTRONICS

52 / 152 page

Application information

ST25R3920

52/152

DS13261 Rev 9

Writing data to addressable registers (Register Write mode)

After the I2C slave address the address of the register to be written is sent using the same

then followed by one or more data bytes. If more than one data byte is sent, the data is

stored in subsequent registers starting form the initial register address by incrementing the

target address by one for each new data byte.

Figure 18 and Figure 19 show, respectively, how to write a single byte into a register and

how to write multiple bytes into subsequent registers using address auto-incrementing.

Figure 18. Writing a single register

Figure 19. Writing register data with auto-incrementing address

Reading data from addressable registers (Register Read mode)

After the I2C slave address the address of the register to be read is sent using the same

byte the ST25R3920 sends data bytes to the SDA output as long as the MCU keeps SCL.

The Register Read mode also supports address auto-incrementing. If the addressed

Table 10. I2C interface and interrupt signal lines

Name

Signal

Signal level

Description

I2C_EN

Digital input

CMOS

Pull to VDD_D for I2C operation

MISO (SDA)

Digital output

I2C data line

SCLK (SCL)

Digital input

I2C clock

IRQ

Digital output

Active high - Interrupt output pin

MS51653V2

SCL

SDA

Slave address

Data

MS51654V3

SCL

SDA

0 0

Data moved to address

<R5-R0> + n

Slave address

Data moved to address

<R5-R0> + 0

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