UPD784938 Datasheet, PDF (156/733 Pages) NEC – 16-Bit Single-Chip Microcontrollers

CHAPTER 6 PORT FUNCTIONS
6.6.2 I/O mode/control mode setting
The port 4 input/output mode is set for each pin by means of the port 4 mode register (PM4) as shown in Figure 6-38.
When port 4 is used as the address/data bus, it is set by means of the memory expansion mode register (MM: See Figure
24-1) as shown in Table 6-6.
Figure 6-38. Port 4 Mode Register (PM4) Format
PM4
7
6
5
4
3
2
1
0 Address After reset R/W
PM47 PM46 PM45 PM44 PM43 PM42 PM41 PM40 0FF24H
FFH
R/W
P4n P4n Pin Input/Output Mode Specification
(n = 0 to 7)
0 Output mode (output buffer on)
1 Intput mode (output buffer off)
Table 6-6. Port 4 Operation Modes
MM3
0
0
0
0
0
0
1
1
MM Bits
MM2 MM1
0
0
0
1
1
0
1
0
1
1
1
1
0
0
0
0
MM0
0
1
0
1
0
1
0
1
Operation Mode
Port
Address/data bus (AD0 to AD7)
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Preliminary User’s Manual U13987EJ1V0UM00