MC68HC812A4 Datasheet, PDF (93/342 Pages) Motorola, Inc – 16-bit device composed of standard on-chip peripheral modules connected by an intermodule bus. Modules include

Advance Information — MC68HC812A4
Section 6. Bus Control and Input/Output (I/O)
6.1 Contents
6.2 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .93
6.3 Detecting Access Type from External Signals . . . . . . . . . . . . .94
6.4 Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .95
6.4.1 Port A Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .96
6.4.2 Port A Data Direction Register . . . . . . . . . . . . . . . . . . . . . . .96
6.4.3 Port B Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .97
6.4.4 Port B Data Direction Register . . . . . . . . . . . . . . . . . . . . . . .97
6.4.5 Port C Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .98
6.4.6 Port C Data Direction Register . . . . . . . . . . . . . . . . . . . . . . .99
6.4.7 Port D Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . .100
6.4.8 Port D Data Direction Register . . . . . . . . . . . . . . . . . . . . . .101
6.4.9 Port E Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . .102
6.4.10 Port E Data Direction Register . . . . . . . . . . . . . . . . . . . . . .103
6.4.11 Port E Assignment Register . . . . . . . . . . . . . . . . . . . . . . . .104
6.4.12 Pullup Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . .107
6.4.13 Reduced Drive Register . . . . . . . . . . . . . . . . . . . . . . . . . . .108
6.2 Introduction
Internally the MCU has full 16-bit data paths, but depending upon the
operating mode and control registers, the external bus may be 8 or 16
bits. There are cases where 8-bit and 16-bit accesses can appear on
adjacent cycles using the LSTRB signal to indicate 8-bit or 16-bit data.
Advance Information
MOTOROLA
Bus Control and Input/Output (I/O)
MC68HC812A4 — Rev. 3.0
93