Section 7 I/O Ports
7.1
Overview
The H8/3437 Series has eight 8-bit input/output ports, one 7-bit input/output port, and one 3-bit
input/output port, and are 8-bit input port.
Table 7.1 lists the functions of each port in each operating mode. As table 7.1 indicates, the port
pins are multiplexed, and the pin functions differ depending on the operating mode.
Each port has a data direction register (DDR) that selects input or output, and a data register (DR)
that stores output data. If bit manipulation instructions will be executed on the port data direction
registers, see “Notes on Bit Manipulation Instructions” in section 2.5.5, Bit Manipulations.
Ports 1, 2, 3, 4, 6, 9, A, and B can drive one TTL load and a 90-pF capacitive load. Ports 5 and 8
can drive one TTL load and a 30-pF capacitive load. Ports 1 and 2 can drive LEDs (with 10-mA
current sink). Ports 1 to 6, 8, 9, A, and B can drive a darlington transistor. Ports 1 to 3, 6, A, and B
have built-in MOS pull-up transistors.
For block diagrams of the ports, see appendix C, I/O Port Block Diagrams.
Pins P86 in port 8, P97 in port 9, and PA4, PA5, PA6, and PA7 in port A can be driven to operate as
bus buffers. For details, see section 13, I2C Bus Interface.
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HITACHI [ HITACHI SEMICONDUCTOR ]
