L99LD01 datasheet(35/69 Pages) STMICROELECTRONICS

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L99LD01

SPI functional description

During the same sequence outgoing data are shifted out MSB first on the falling edge of the

CSN pin and subsequent bits on the falling edge of the serial clock (SCK). The first byte

corresponds to the Global Status Byte and the second to the previous content of the

addressed register.

Figure 23. SPI write operation

Read mode

The read mode of the device allows to read and to check the state of any register. Incoming

data are sampled on the rising edge of the serial clock (SCK), MSB first. Outgoing data are

shifted out MSB first on the falling edge of the CSN pin and others on the falling edge of the

serial clock (SCK). The first byte corresponds to the Global Status Byte and the second to

the content of the addressed register. In case of a read mode on an unused address, the

‘global status/error’ byte on the SDO pin is following by 00H byte.

In order to avoid inconsistency between the Global status byte and the status register, the

status register contents are frozen during SPI communication.

Figure 24. SPI read operation

Read and clear status command

The read and clear status operation is used to clear the content of the addressed status

CSN

SDO

SDI

0MSB

MSB

LSB

Command Byte

Global Status Byte

(8 bit)

Data

(previous content of register)

Data

(8 bit)

Address

MSB

CSN

SDO

SDI

MSB

LSB

Command Byte

Global Status Byte

(8 bit)

Data

(8 bit)

Don’t care

(8 bit)

0LSB

Address

MSB

L99LD01 Datenblatt(PDF) 35 Page - STMicroelectronics

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