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Section 10 I/O Ports
10.1
Overview
The H8S/2633 Series has 10 I/O ports (ports 1, 3, 7 and A to G), and two input-only port (ports 4
and 9).
Table 10-1 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 C include an open-drain control register (ODR) that controls the on/off state of
the output buffer PMOS.
When ports 10 to 13, 70 to 73, and A to G are used as the output pins for expanded bus control
signals, they can drive one TTL load plus a 50pF capacitance load. Those ports in other cases, and
ports 14 to 17, 3, and 74 to 77, can drive one TTL load and a 30pF capacitance load. All IO ports
can drive Darlington transistors when set to output.
See appendix C, I/O Port Block Diagrams, for a block diagram of each port.
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