L99DZ70XPTR Datasheet, PDF (30/47 Pages) STMicroelectronics – Door actuator driver

Functional description of the SPI
L99DZ70XP
4.1.5
SPI communication flow
At the beginning of each communication the master can read the contents of the <SPI-
frame-ID> register (ROM address 03H) 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 DO 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.
Figure 10. Write and read SPI
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Doc ID 15162 Rev 4