Hitachi H8/3008, Руководство по оборудованию

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Section 7 I/O Ports
7.1 Overview
The H8/3008 has six input/output ports (ports 4, 6, 8, 9, A, and B) and one input-only port (port
7). Table 7.1 summarizes the port functions. The pins in each port are multiplexed as shown in
table 7.1.
Each port has a data direction register (DDR) for selecting input or output, and a data register
(DR) for storing output data. In addition to these registers, port 4 has an input pull-up control
register (PCR) for switching input pull-up transistors on and off.
Ports 4, 6, and 8 can drive one TTL load and a 90-pF capacitive load. Ports 9, A, and B can drive
one TTL load and a 30-pF capacitive load. Ports 4, 6, 8, 9, A, and B can drive a darlington pair.
Pins P8
2
to P8
0
, PA
7
to PA
0
have Schmitt-trigger input circuits.
For block diagrams of the ports see appendix C, I/O Port Block Diagrams.
Table 7.1 Port Functions
Expanded Modes
Port Description Pins Mode 1 Mode 2 Mode 3 Mode 4
Port 4
•
8-bit I/O port
•
Built-in input pull-
up transistors
P4
7
to P4
0
/D
7
to D
0
Data input/output (D
7
to D
0
) and 8-bit generic input/output
8-bit bus mode: generic input/output
16-bit bus mode: data input/output
Port 6
•
8-bit I/O port P6
7
/
φ
Clock output (
φ
) and generic input
P6
6
/
LWR
P6
5
/
HWR
P6
4
/
RD
P6
3
/
AS
Bus control signal output (
LWR
,
HWR
,
RD
,
AS
)
P6
2
/
BACK
P6
1
/
BREQ
P6
0
/
WAIT
Bus control signal input/output (
BACK
,
BREQ
,
WAIT
) and 3-
bit generic input/output
Port 7
•
8-bit I/O port P7
7
/AN
7
/DA
1
P7
6
/AN
6
/DA
0
Analog input (AN
7
, AN
6
) to A/D converter, analog output (DA
1
,
DA
0
) from D/A converter, and generic input
P7
5
to P7
0
/
AN
5
to AN
0
Analog input (AN
5
to AN
0
) to A/D converter, and generic input