Section 7 I/O Ports
7.1
Overview
The H8/3337 Series and H8/3397 Series have six 8-bit input/output ports, one 7-bit input/output
port, and one 3-bit input/output port, and one 8-bit dedicated 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 Manipulation
Instructions.
Ports 1, 2, 3, 4, 6, and 9 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, and 9 can drive a darlington pair. Ports 1 to 3, and 6 have built-in
MOS pull-up transistors.
For block diagrams of the ports, see appendix C, I/O Port Block Diagrams.
Pin P86 of port 8 and pin P97 of port 9 can drive a bus buffer. For details of bus buffer drive, see
section 13, I2C Bus Interface.
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