L99LD01 datasheet(32/69 Pages) STMICROELECTRONICS

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SPI functional description

L99LD01

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DocID025319 Rev 3

Figure 22. SPI global error information output

3.2

Signal description

•

Serial Clock (SCK): this input signal provides the timing of the serial interface. Data

present at Serial Data Input (SDI) is latched on the rising edge of Serial Clock (SCK).

Data on Serial Data Out (SDO) is shifted out at the falling edge of Serial Clock (SCK).

•

Serial Data Input (SDI): This input is used to transfer data serially into the device. It

receives the data to be written. Values are latched on the rising edge of Serial Clock

(SCK).

•

Serial Data Output (SDO): this output signal is used to transfer data serially out of the

device. Data is shifted out on the falling edge of Serial Clock (SCK). SDO also reflects

the status of the <Global Error Flag> (Bit 7 of the <Global Status Register>) while CSN

is low and no clock signal is present

•

Chip Select Not (CSN): when this input signal is High, the device is deselected and

Serial Data Output (SDO) is high impedance. Driving this input Low enables the

communication. The communication must start and stop on a Low level of Serial Clock

(SCK).

3.3

SPI protocol

3.3.1

SDI, SDO format

SDI format during each communication frame starts with a command byte.

It begins with two bits of operating code (OC0, OC1) which specify the type of operation

(read, write, read and clear status, read device information) and is followed by a 6 bit

address (A0:A5). The command byte is followed by an input data byte (D0:D15).

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