MC9S08JM60CLH Freescale, MC9S08JM60CLH Datasheet - Page 66

• Manufacturer Part Number: MC9S08JM60CLH
• Manufacturer: Freescale

Specifications of MC9S08JM60CLH

• Cpu Family: HCS08
• Device Core Size: 8b
• Frequency (max): 24MHz
• Interface Type: SCI/SPI
• Total Internal Ram Size: 4KB
• # I/os (max): 51
• Number Of Timers - General Purpose: 8
• Operating Supply Voltage (typ): 3.3/5V
• Operating Supply Voltage (max): 5.5V
• Operating Supply Voltage (min): 2.7V
• On-chip Adc: 12-chx12-bit
• Instruction Set Architecture: CISC
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Pin Count: 64
• Package Type: LQFP
• Program Memory Type: Flash
• Program Memory Size: 60KB
• Lead Free Status / RoHS Status: Compliant

Chapter 5 Resets, Interrupts, and System Configuration
Each of these sources, with the exception of the background debug forced reset, has an associated bit in
the system reset status (SRS) register.
5.4
Computer Operating Properly (COP) Watchdog
The COP watchdog is intended to force a system reset when the application software fails to execute as
expected. To prevent a system reset from the COP timer (when it is enabled), application software must
reset the COP counter periodically. If the application program gets lost and fails to reset the COP counter
before it times out, a system reset is generated to force the system back to a known starting point.
After any reset, the COP watchdog is enabled (see
Section 5.7.4, “System Options Register 1
(SOPT1),”
for additional information). If the COP watchdog is not used in an application, it can be disabled by
clearing COPT bits in SOPT1.
The COP counter is reset by writing 0x55 and 0xAA (in this order) to the address of SRS during the
selected timeout period. Writes do not affect the data in the read-only SRS. As soon as the write sequence
is done, the COP timeout period is restarted. If the program fails to do this during the time-out period, the
MCU will reset. Also, if any value other than 0x55 or 0xAA is written to SRS, the MCU is immediately
reset.
The COPCLKS bit in SOPT2 (see
Section 5.7.5, “System Options Register 2
(SOPT2),” for additional
information) selects the clock source used for the COP timer. The clock source options are either the bus
clock or an internal 1 kHz LPO clock source. With each clock source, there are three associated time-outs
controlled by the COPT bits in SOPT1.
Table 5-6
summaries the control functions of the COPCLKS and
COPT bits. The COP watchdog defaults to operation from the 1 kHz LPO clock source and the longest
10
time-out (2
cycles).
When the bus clock source is selected, windowed COP operation is available by setting COPW in the
SOPT2 register. In this mode, writes to the SRS register to clear the COP timer must occur in the last 25%
of the selected timeout period. A premature write immediately resets the MCU. When the 1 kHz LPO clock
source is selected, windowed COP operation is not available.
The COP counter is initialized by the first writes to the SOPT1 and SOPT2 registers and after any system
reset. Subsequent writes to SOPT1 and SOPT2 have no effect on COP operation. Even if the application
will use the reset default settings of COPT, COPCLKS, and COPW bits, the user must write to the
write-once SOPT1 and SOPT2 registers during reset initialization to lock in the settings. This will prevent
accidental changes if the application program gets lost.
The write to SRS that services (clears) the COP counter must not be placed in an interrupt service routine
(ISR) because the ISR could continue to be executed periodically even if the main application program
fails.
If the bus clock source is selected, the COP counter does not increment while the MCU is in background
debug mode or while the system is in stop mode. The COP counter resumes when the MCU exits
background debug mode or stop mode.
If the 1 kHz LPO clock source is selected, the COP counter is re-initialized to zero upon entry to either
background debug mode or stop mode and begins from zero upon exit from background debug mode or
stop mode.
MC9S08JM60 Series Data Sheet, Rev. 3
66
Freescale Semiconductor