Section 5 I/O Ports; Overview - Hitachi H8S/2678 Series Reference Manual

Section 5 I/O Ports

5.1

Overview

The H8S/2678 Series has fifteen I/O ports (ports 1 to 3, P50 to P53, 6 to 8, and A to H), and two
input-only ports (port 4 and P54 to P57).
Table 5.1 summarizes the port functions. The pins of each port also have other functions.
Each port includes a data direction register (DDR) that controls input/output (not provided for the
input-only ports), a data register (DR) that stores output data, and a port register (PORT) used to
read the pin states.
Ports A to E have a built-in MOS input pull-up function, and in addition to DR and DDR, have a
MOS input pull-up control register (PCR) to control the on/off status of MOS input pull-ups.
Ports 3 and A include an open-drain control register (ODR) that controls the on/off status of the
output buffer PMOS.
Ports A to H can drive a single TTL load and 50 pF capacitive load, and ports 1, 2, 3, 5 (P50 to
P53), 6, 7, and 8 can drive a single TTL load and 30 pF capacitive load.
Ports 1 and 2 have Schmitt-trigger input circuits. Ports 5, 6, 8, F (PF1, PF2), and H (PH2, PH3)
are Schmitt-trigger inputs when used as IRQ inputs.
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