Datasheet

MC68HC908GR16 Data Sheet, Rev. 5.0
Freescale Semiconductor 83
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.
Figure 6-1. COP Block Diagram
COPCTL WRITE
CGMXCLK
RESET VECTOR FETCH
RESET CIRCUIT
RESET STATUS REGISTER
INTERNAL RESET SOURCES
12-BIT COP PRESCALER
CLEAR ALL STAGES
6-BIT COP COUNTER
COP DISABLE
RESET
COPCTL WRITE
CLEAR
COP MODULE
COPEN (FROM SIM)
COP COUNTER
COP CLOCK
COP TIMEOUT
STOP INSTRUCTION
(FROM CONFIG)
COP RATE SEL
(FROM CONFIG)
CLEAR STAGES 5–12