ST90158 - SERIAL PERIPHERAL INTERFACE (SPI)
SERIAL PERIPHERAL INTERFACE (Cont’d)
9.5.7 S-Bus Interface
The S-bus is a three-wire bidirectional data-bus,
SPI Working with S-bus
2
possessing functional features similar to the I C-
The S-bus protocol uses the same pin configura-
2
bus. As opposed to the I C-bus, the Start/Stop
2
tion as the I C-bus for generating the SCL and
conditions are determined by encoding the infor-
mation on 3 wires rather than on 2, as shown in
Figure 72. The additional line is referred as SEN.
SDA lines. The additional SEN line is managed
through a standard ST9 I/O port line, under soft-
ware control (see Figure 68).
2
Figure 71. Mixed S-bus and I C-bus System
SCL
SDA
SEN
1
2
3
4
5
6
STOP
VA00440
START
n
Figure 72. S-bus Configuration
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