CHAPTER 13 SERIAL INTERFACE CHANNEL 0
227
User’s Manual U11302EJ4V0UM
(a) Bus release signal (REL)
The bus release signal is identified when the SB0 (SB1) line has changed from low level to high level while
the SCK0 line is high level (without serial clock output).
This signal is output by the master device.
Figure 13-11. Bus Release Signal
The bus release signal indicates that the master device is going to transmit an address to the slave device.
The slave device incorporates hardware to detect the bus release signal.
Caution
If the SB0 (SB1) line changes from low level to high level while the SCK0 line is high
level, it is recognized as a bus release signal. Therefore, if the changing timing of
the bus fluctuates because of substrate capacitance, etc., it may be recognized as
a bus release signal even while data is being transmitted. Care should therefore
be taken in the wiring.
(b) Command signal (CMD)
The command signal is identified when the SB0 (SB1) line has changed from high level to low level while
the SCK0 line is high level (without serial clock output). This signal is output by the master device.
Figure 13-12. Command Signal
The command signal indicates that from this point, the master will send a command to the slave (however,
command signals following bus release signals indicate that an address will be sent).
The slave incorporates hardware to detect command signals.
Caution
If the SB0 (SB1) line changes from high level to low level while the SCK0 line is high
level, it is recognized as a command signal. Therefore, if the changing timing of
the bus fluctuates because of substrate capacitance, etc., it may be recognized as
a command signal even while data is being transmitted. Care should therefore be
taken in the wiring.
SCK0
"H"
SB0 (SB1)
SCK0
"H"
SB0 (SB1)
Содержание mPD780208 Subseries
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