Datasheet

MC68HC908JL3E Family Data Sheet, Rev. 4
Freescale Semiconductor 123
Chapter 13
Computer Operating Properly (COP)
13.1 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
CONFIG1 register.
13.2 Functional Description
Figure 13-1 shows the structure of the COP module.
Figure 13-1. COP Block Diagram
COPCTL WRITE
2OSCOUT
RESET VECTOR FETCH
SIM RESET CIRCUIT
RESET STATUS REGISTER
INTERNAL RESET SOURCES
(1)
SIM
CLEAR STAGES 5–12
12-BIT SIM COUNTER
CLEAR ALL STAGES
COPD (FROM CONFIG1)
RESET
COPCTL WRITE
CLEAR
COP MODULE
COPEN (FROM SIM)
COP COUNTER
NOTE: See Chapter 5 System Integration Module (SIM) for more details.
COP CLOCK
COP TIMEOUT
COP RATE SEL
(COPRS FROM CONFIG1)
6-BIT COP COUNTER