MC68HC912BD32 Datasheet, PDF (47/292 Pages) Freescale Semiconductor, Inc – Advance Information

Freescale Semiconductor, Inc.
Operating Modes and Resource Mapping
Operating Modes and Resource Mapping
Contents
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Operating Modes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Background Debug Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Internal Resource Mapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Memory Maps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Introduction
Eight possible operating modes determine the operating configuration of
the MC68HC912BD32. Each mode has an associated default memory
map and external bus configuration. After reset, most system resources
can be mapped to other addresses by writing to the appropriate control
registers.
Operating Modes
The operating mode out of reset is determined by the states of the
BKGD, MODB, and MODA pins during reset.
The SMODN, MODB, and MODA bits in the MODE register show current
operating mode and provide limited mode switching during operation.
The states of the BKGD, MODB, and MODA pins are latched into these
bits on the rising edge of the reset signal. During reset an active pullup
is connected to the BKGD pin (as input) and active pulldowns are
connected to the MODB and MODA pins. If an open occurs on any of
these pins, the device will operate in normal single-chip mode.
1-mode
Operating Modes and Resource Mapping
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MC68HC912BD32 Rev 1.0