Datasheet

Table Of Contents
Advance Information MC68HC908GP20Rev 2.1
146 Freescale Semiconductor
9.2 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.
9.3 Functional Description
Figure 9-1 shows the structure of the COP module.
Figure 9-1. COP Block Diagram
COPCTL WRITE
CGMXCLK
RESET VECTOR FETCH
RESET CIRCUIT
RESET STATUS REGISTER
INTERNAL RESET SOURCES
CLEAR STAGES 5–12
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)