L99LD01 datasheet(33/69 Pages) STMICROELECTRONICS

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L99LD01

SPI functional description

At the beginning of each communication the master device read the contents of the <SPI-

frame-ID> register (ROM address 3Eh) of the slave device. This 8 bit register indicates the

SPI frame length (24 bit) and the availability of additional features.

Each communication frame consists of a command byte which is followed by 2 data bytes.

The data returned on SDO within the same frame always starts with the <Global Status

Byte>. It provides general status information about the device. It is followed by 2 data bytes

(i.e. "in-frame-response").

For write cycles the <Global Status Byte> is followed by the previous content of the

addressed register.

SDO format during each communication frame starts with a specific byte called Global

Status Byte (see Section 3.3.2). This byte is followed by two output data byte (D0:D7,

D8:D15).

3.3.2

Global status byte description

The data shifted out on SDO during each communication starts with a specific byte called

Global Status Byte. This one is used to inform the microcontroller about global faults which

can be happened on the channel part (like thermal warning, OVL,...) or on the SPI interface

(like communication error,...). This specific register has the following format.

Table 4. Command byte (8 bit)

Bit

2322

2120

1918

1716

Name

OC1

OC0

Table 5. Input data byte

Data Byte 1

Data Byte 0

Bit

987

432

Name

D15

D14

D13

D12

D11

D10

Table 6. Global status byte

Bit

Name

GEF

Comm_Err

Not (chip reset or

Comm_Error)

LED overload Temp. warning Overvoltage

VCC1

Error

Fail safe

Table 7. Output data byte

Data Byte 1

Data Byte 0

Bit

987

432

Name

D15

D14

D13

D12

D11

D10

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