MC68HC908AT32 Datasheet, PDF (125/378 Pages) Freescale Semiconductor, Inc – Microcontrollers

Chapter 13
Computer Operating Properly Module (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 periodically clearing the COP counter.
13.2 Functional Description
CGMXCLK
12-BIT COP PRESCALER
STOP INSTRUCTION
NTERNAL RESET SOURCES
RESET VECTOR FETCH
COPCTL WRITE
COPD FROM CONFIG
RESET
COPCTL WRITE
COPRS FROM CONFIG
6-BIT COP COUNTER
CLEAR COP
COUNTER
RESET
RESET STATUS
REGISTER
Figure 13-1. COP Block Diagram
The COP counter is a free-running 6-bit counter preceded by the 12-bit system integration module (SIM)
counter. COP timeouts are determined strictly by the CGM crystal oscillator clock signal (CGMXCLK), not
the CGMOUT signal (see Figure 13-1).
MC68HC908AT32 Data Sheet, Rev. 3.1
Freescale Semiconductor
125