BTS54040-LBF_15 Datasheet, PDF (54/67 Pages) Infineon Technologies AG – SPI Power Controller

BTS54040-LBF
Serial Peripheral Interface (SPI)
9.5
SPI Protocol
The relationship between SI and SO content during SPI communication is shown in Figure 30. SI line represents
the frame sent from the µC and SO line is the answer provided by BTS54040-LBF. The “(previous response)”
means that the frame sent back depends on the command frame sent from the µC before.
SI
frame A
frame B
frame C
SO
(previous
response )
response to
frame A
response to
frame B
SPI _ SI2 SO.emf
Figure 30 Relationship between SI and SO during SPI communication
The SPI protocol provides the answer to a command frame only with the next transmission triggered by the µC.
Although the biggest majority of commands and frames implemented in BTS54040-LBF can be decoded without
the knowledge of what happened before, it is advisable to consider what the µC sent in the previous transmission
to decode BTS54040-LBF response frame completely.
More in detail, the sequence of commands to “read” and “write” the content of a register will look as follows:
SI
write register A
read register A
(new command )
(previous
SO
response )
Standard
diagnostic
register A
content
SPI_RWseq.emf
Figure 31 Register content sent back to µC
There are 3 special situations where the frame sent back to the µC doesn't depend on the previous received frame:
• in case an error in transmission happened during the previous frame (for instance, the clock pulses were not
multiple of 8), shown in Figure 32
• when BTS54040-LBF logic supply comes out of Power-On reset condition, as shown in Figure 33
• when V_S < V_SMON and DCR.MUX ≠ 111_B, as shown in Figure 34
SI
frame A
(error in transmission )
(new command)
SO
(previous response )
Standard diagnostic + TER
Figure 32 BTS54040-LBF response after an error in transmission
SPI_SO_TER.emf
Data Sheet
54
Rev. 2.1, 2014-12-05