MC68HC11G5 Datasheet, PDF (19/195 Pages) Motorola, Inc – High-density Complementary Metal Oxide Semiconductor (HCMOS) Microcontroller

Freescale Semiconductor, Inc.
SECTION 2
OPERATING MODES AND SIGNAL DESCRIPTION
This section describes the operating modes and signals of the MC68HC11G5 MCU.
2.1 OPERATING MODES
During reset the MC68HC11G5 uses two mode select pins, MODA and MODB, to select one of two
normal modes or one of two special operating modes. The normal operating modes are the single
chip mode, which allows maximum use of the pins for on-chip peripheral functions, and the
expanded non-multiplexed mode which allows access to the 64 kbytes of memory space including
the internal RAM, ROM (if present), and register spaces. The special operating modes are the
bootstrap mode (which causes all vectors to be fetched from the on-chip bootstrap ROM), and the
test mode (which is an expanded mode allowing special testing functions on the MCU subsystems).
The special operating modes have access to certain privileged control bits which are not available
in the normal operating modes.
Mode selection, according to the values encoded on the mode select pins (MODA and MODB), is
shown in Table 2-1. The states of MODA and MODB, captured during reset determine the logic state
of the Special Mode (SMOD) and the Mode A Select (MDA) control bits in the HPRIO register.
Table 2-1. Mode Select Summary
Input Pins
MODA MODB
0
1
1
1
0
0
1
0
Mode Selected
Single Chip
Expanded Non-Multiplexed
Bootstrap
Test
Latched at Reset
SMOD
MDA
0
0
0
1
1
0
1
1
OPERATING MODES AND SIGNAL DESCRIPTION
2-1
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