Section 9 I/O Ports; Overview; I/O Ports - Hitachi H8S/2646 Hardware Manual

Hitachi 16-bit single-chip microcomputer h8s/2646 series
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Section 9 I/O Ports

9.1

Overview

The H8S/2646 Series has 13 I/O ports (ports 1 to 3, 5 and A to F, H, J, K), and two input-only port
(ports 4 and 9).
Table 9-1 summarizes the port functions. The pins of each port also have other functions.
Each I/O port includes a data direction register (DDR) that controls input/output, a data register
(DR) that stores output data, and a port register (PORT) used to read the pin states. The input-only
ports do not have a DR or DDR register.
Ports A to E have a built-in pull-up MOS function, and in addition to DR and DDR, have a MOS
input pull-up control register (PCR) to control the on/off state of MOS input pull-up.
Ports 3, and A to F include an open-drain control register (ODR) that controls the on/off state of
the output buffer PMOS.
When ports A to F are used as the output pins for expanded bus control signals, they can drive one
TTL load plus a 50pF capacitance load. Ports other than A to F can drive one TTL load and a
30pF capacitance load. All I/O ports can drive Darlington transistors when set to output. Ports 1
and A to C can drive a LED (10 mA sink current), and some of the pins in ports A to E and F can
be used as LCD driver pins.
Port 1 pins P16 and P14, and port 3 pins P35 and P32 are Schmitt-trigger inputs.
See Appendix C, I/O Port Block Diagrams, for a block diagram of each port.
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