MC68HC705C8A Datasheet, PDF (59/222 Pages) Motorola, Inc – HCMOS Microcontroller Unit

Technical Data — MC68HC705C8A
Section 5. Resets
5.1 Contents
5.2 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59
5.3 Reset Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59
5.3.1 Power-On Reset (POR) . . . . . . . . . . . . . . . . . . . . . . . . . . . .60
5.3.2 External Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .60
5.3.3 Programmable and Non-Programmable
COP Watchdog Resets . . . . . . . . . . . . . . . . . . . . . . . . . .60
5.3.3.1 Programmable COP Watchdog Reset . . . . . . . . . . . . . . .61
5.3.3.2 Non-Programmable COP Watchdog . . . . . . . . . . . . . . . .64
5.3.4 Clock Monitor Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .65
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. 2.0
MOTOROLA
Resets
Technical Data
59