Port 2 ( Μ Pd78014Y Subseries) - NEC 78014Y Series User Manual

6.2.4 Port 2 ( µ PD78014Y Subseries)
Port 2 is an 8-bit input/output port with output latch. P20 to P27 pins can be set to the input mode/output mode
bit-wise with the port mode register 2 (PM2). When P20 to P27 pins are used as input ports, an on-chip pull-up resistor
can be connected to them in 8-bit units with a pull-up resistor option register (PUO).
Alternate functions include serial interface data input/output, clock input/output, automatic transmit/receive busy
input, and strobe output.
RESET input sets port 2 to input mode.
Figures 6-8 and 6-9 show a block diagram of port 2.
Cautions 1. If used as alternate function pin, set the input/output latch according to the functions. Refer
www.DataSheet4U.com
to Figure 16-6 Serial Operating Mode Register 0 Format and Figure 17-3 Serial Operating Mode
Register 1 Format for setting.
2. When the status of pins is read in the SBI mode, set PM2n of the PM2 to 1 (n = 5 or 6) (refer
to 16.4.3 SBI mode operation (10) Distinction method of slave busy state).
Figure 6-8. P20, P21, P23 to P26 Block Diagrams ( µ PD78014Y Subseries)
WR
PUO
PUO2
RD
WR
PORT
Output Latch
(P20, P21,
P23 to P26)
WR
PM
PM20, PM21,
PM23 to PM26
Alternate
Function
PUO : Pull-up resistor option register
PM : Port mode register
RD : Port 2 read signal
WR : Port 2 write signal
CHAPTER 6 PORT FUNCTIONS
Selector
V
DD
P-ch
P20/SI1,
P21/SO1,
P23/STB,
P24/BUSY,
P25/SI0/SB0/
SDA0,
P26/SO0/SB1/
SDA1
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