Datasheet

MC68HC908GZ16 • MC68HC908GZ8 Data Sheet, Rev. 4
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
BUSCLKX4
RESET VECTOR FETCH
SIM RESET CIRCUIT
RESET STATUS REGISTER
INTERNAL RESET SOURCES
(1)
SIM MODULE
CLEAR STAGES 5–12
12-BIT SIM COUNTER
CLEAR ALL STAGES
COPD (FROM CONFIG1)
RESET
COPCTL WRITE
CLEAR
COP MODULE
COPEN (FROM SIM)
1. See Chapter 16 System Integration Module (SIM) for more details.
COP CLOCK
COP TIMEOUT
COP RATE SELECT
(COPRS FROM CONFIG1)
6-BIT COP COUNTER
COP COUNTER