(6) Pin configuration
The configuration of the serial clock pin (SCK) and the serial data bus pin SB0 is as shown below.
(a) SCK .................... Pin for input/output of serial clock
Master ........ CMOS, push-pull output
Slave ........... Schmitt input
(b) SB0 .................... Serial data input/output dual- function pin
Since the serial data bus line output is N-ch open-drain, an external pull-up resistor is necessary.
Master Device
Clock Output
(Clock Input)
N-ch Open Drain
SO
SI
Note
Since the N-ch open drain must be turned off during data reception, FFH should be written to SIO
beforehand. It can always be turned off during transmission.
However, when the wake-up function specification bit (WUP) is 1, the N-ch transistor is always off, and
therefore FFH need not be written to SIO prior to reception.
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CHAPTER 5. PERIPHERAL HARDWARE FUNCTIONS
For both master and slave, output is N-ch open-drain, input is Schmitt input.
Fig. 5-48 Pin Configuration Diagram
Serial Clock
SB0
Serial Data Bus
R
L
SB0
N-ch Open Drain
Slave Device
(Clock Output)
Clock Input
SO
SI