Freescale Semiconductor, Inc.
Technical Data — MC68HC705C8A
Section 5. Resets
5.1 Contents
5.2
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61
5.3
Reset Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61
Power-On Reset (POR) . . . . . . . . . . . . . . . . . . . . . . . . . . . .62
External Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .62
Programmable and Non-Programmable
5.3.1
5.3.2
5.3.3
COP Watchdog Resets . . . . . . . . . . . . . . . . . . . . . . . . . .62
Programmable COP Watchdog Reset . . . . . . . . . . . . . . .63
Non-Programmable COP Watchdog . . . . . . . . . . . . . . . .66
Clock Monitor Reset. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .67
5.3.3.1
5.3.3.2
5.3.4
5.2 Introduction
This section describes how resets initialize the microcontroller unit
(MCU).
5.3 Reset Sources
A reset immediately stops the operation of the instruction being
executed, initializes certain control bits, and loads the program counter
with a user-defined reset vector address. These conditions produce a
reset:
• Power-on reset (POR) — Initial power-up
• External reset — A logic 0 applied to the RESET pin
• Internal programmable computer operating properly (COP)
watchdog timer reset
• Internal non-programmable COP watchdog timer reset
• Internal clock monitor reset
MC68HC705C8A — Rev. 3
MOTOROLA
Technical Data
Resets
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