MC68HC908LJ12CPB FREESCALE [Freescale Semiconductor, Inc], MC68HC908LJ12CPB Datasheet - Page 371

• Manufacturer Part Number: MC68HC908LJ12CPB
• Description: 8-bit microcontroller units
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

Computer Operating Properly (COP)
20.3 Functional Description
Technical Data
372
INTERNAL RESET SOURCES
(COPRS FROM CONFIG1)
(COPD FROM CONFIG1)
RESET VECTOR FETCH
STOP INSTRUCTION
COPEN (FROM SIM)
NOTE:
COPCTL WRITE
COPCTL WRITE
COP RATE SEL
COP DISABLE
RESET
ICLK
Figure 20-1
The COP counter is a free-running 6-bit counter preceded by a 12-bit
prescaler counter. If not cleared by software, the COP counter overflows
and generates an asynchronous reset after 2
cycles, depending on the state of the COP rate select bit, COPRS, in the
CONFIG1 register. With a 2
ICLK gives a COP timeout period of 174ms. Writing any value to location
$FFFF before an overflow occurs prevents a COP reset by clearing the
COP counter and stages 12 through 5 of the prescaler.
Service the COP immediately after reset and before entering or after
exiting STOP Mode to guarantee the maximum time before the first COP
counter overflow.
Figure 20-1. COP Block Diagram
Computer Operating Properly (COP)
12-BIT COP PRESCALER
shows the structure of the COP module.
COP CLOCK
COP COUNTER
6-BIT COP COUNTER
CLEAR
13
– 2
4
ICLK cycle overflow option, a 47-kHz
RESET STATUS REGISTER
18
MC68HC908LJ12
– 2
RESET CIRCUIT
Freescale Semiconductor
4
or 2
13
– 2
4
—
ICLK
Rev. 2.1