MC68HC908GR8A_07 Datasheet, PDF (79/260 Pages) Freescale Semiconductor, Inc – Microcontrollers

Chapter 6
Computer Operating Properly (COP) Module
6.1 Introduction
The computer operating properly (COP) module contains a free-running counter that generates a reset if
allowed to overflow. The COP module helps software recover from runaway code. Prevent a COP reset
by clearing the COP counter periodically. The COP module can be disabled through the COPD bit in the
CONFIG register.
6.2 Functional Description
Figure 6-1 shows the structure of the COP module.
CGMXCLK
SIM MODULE
12-BIT SIM COUNTER
SIM RESET CIRCUIT
RESET STATUS REGISTER
INTERNAL RESET SOURCES⁽¹⁾
STOP INSTRUCTION
COPCTL WRITE
COP CLOCK
COP MODULE
COPEN (FROM SIM)
COPD (FROM CONFIG1)
RESET
COPCTL WRITE
COP RATE SELECT
(COPRS FROM CONFIG1)
6-BIT COP COUNTER
CLEAR
COP COUNTER
1. See Chapter 14 System Integration Module (SIM) for more details.
Figure 6-1. COP Block Diagram
MC68HC908GR8A • MC68HC908GR4A Data Sheet, Rev. 5
Freescale Semiconductor
79