NEC 78014Y Series, User Manual

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CHAPTER 15 SERIAL INTERFACE CHANNEL 0 (
µ
PD78014 Subseries)
302
Caution Because the N-ch open-drain output must be set to high-impedance at the time of data 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.
(5) Pin configuration
The serial clock pin SCK0 and serial data bus pin SB0 (SB1) have the following configurations.
(a) SCK0 ............ Serial clock input/output pin
<1> Master .. CMOS and push-pull output
<2> Slave .... Schmitt input
(b) SB0 (SB1) .... Serial data input/output dual-function pin
Both master and slave devices have an N-ch open-drain output and a Schmitt input.
Because the serial data bus line has an N-ch open-drain output, an external pull-up resistor is necessary.
Figure 15-27. Pin Configuration
Master Device
Clock Output
(Clock Input)
N-ch Open-Drain
SO0
SI0
SCK0 SCK0
Serial Clock
SB0 (SB1)
R
L
SB0 (SB1)
Serial Data Bus
Slave Device
(Clock Output)
Clock Input
N-ch Open-Drain
SO0
SI0
V
DD