Port 4 - Hitachi H8/329 Series Hardware Manual

5.5 Port 4

Port 4 is an 8-bit input/output port that also provides pins for interrupt input (IRQ
trigger input, system clock (Ø) output, and bus control signals (in the expanded modes).
Pins P4 to P4 have different functions in different modes. Pins P4
7 3
functions in all modes. Table 5-11 lists the pin functions.
Table 5-11. Port 4 Pin Functions
Pin Expanded modes
P4 P4 input/output , IRQ
0 0
P4 P4 input/output and IRQ
1 1
P4 P4 input/output and IRQ
2 2
P4 RD output
3
P4 WR output
4
P4 AS output
5
P4 Ø output
6
P4 WAIT input
7
Pins of port 4 can drive a single TTL load and a 90pF capacitive load when they are used as output
pins.
Table 5-12 details the port 4 registers.
Table 5-12. Port 4 Registers
Name
Port 4 data direction register
Port 4 data register
Notes: *1 Bit 6 is read-only.
*2 Bit 6 is undetermined. Other bits are initially "0."
Single-chip mode
input, and ADTRG input (simultaneously)
2
input (simultaneously)
1
input (simultaneously)
0
P4 input/output
3
P4 input/output
4
P4 input/output
5
P4 input or Ø output
6
P4 input/output
7
Abbreviation Read/Write
P4DDR W
*1
P4DR R/W
88
to IRQ
0
to P4 have the same
2 0
Initial value
H'40 (modes 1 and 2) H'FFB5
H'00 (mode 3)
*2
Undetermined
), A/D
2
Address
H'FFB7