NEC 78014Y Series User Manual page 363

(5) Pin configuration
The serial clock pin SCK0 and serial data bus pin SB0 (SB1) have the following configurations.
(a) SCK0
(b) SB0 (SB1) : Serial data input/output dual-function pin
Because the serial data bus line has an N-ch open-drain output, an external pull-up resistor is necessary.
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Caution Because the N-ch open-drain output must be set to high-impedance at the time of data
CHAPTER 16 SERIAL INTERFACE CHANNEL 0 ( µ PD78014Y Subseries)
: Serial clock input/output pin
<1> Master : CMOS and push-pull output
<2> Slave : Schmitt input
Both master and slave devices have an N-ch open-drain output and a Schmitt input.
Master Device
Clock Output
(Clock Input)
N-ch Open-Drain
SO0
SI0
reception, write FFH to the serial I/O shift register 0 (SIO0) in advance. However, when the wake-
up function specification bit (WUP) = 1, the N-ch open-drain output will always be set to high-
impedance. Thus, it is not necessary to write FFH to SIO0 before reception.
Figure 16-28. Pin Configuration
SCK0 SCK0
Serial Clock
V
DD
R
L
SB0 (SB1) SB0 (SB1)
Serial Data Bus
Slave Device
(Clock Output)
Clock Input
N-ch Open-Drain
SO0
SI0
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