MPC555CME Freescale Semiconductor, MPC555CME Datasheet - Page 225

• Manufacturer Part Number: MPC555CME
• Description: KIT EVALUATION FOR MPC555
• Manufacturer: Freescale Semiconductor
• Type: Microcontrollerr

Specifications of MPC555CME

• Contents: Module Board, Installation Guide, Power Supply, Cable, Software and more
• Processor To Be Evaluated: MPC555
• Data Bus Width: 32 bit
• Interface Type: RS-232
• For Use With/related Products: MPC555
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

MPC555
USER’S MANUAL
Although the writes must occur in the correct order prior to time-out, any number of
instructions may be executed between the writes. This allows interrupts and excep-
tions to occur, if necessary, between the two writes.
Although most software disciplines support the watchdog concept, different systems
require different time-out periods. For this reason, the software watchdog provides a
selectable range for the time-out period.
In
SWTC field is then loaded into a 16-bit decrementer clocked by the system clock. An
additional divide by 2048 prescaler is used if necessary. The decrementer begins
counting when loaded with a value from the software watchdog timing count field
(SWTC). After the timer reaches 0x0, a software watchdog expiration request is issued
to the reset or NMI control logic.
Upon reset, the value in the SWTC is set to the maximum value and is again loaded
into the software watchdog register (SWR), starting the process over. When a new val-
ue is loaded into the SWTC, the software watchdog timer is not updated until the ser-
vicing sequence is written to the SWSR. If the SWE is loaded with the value zero, the
modulus counter does not count.
Figure
Not 0x556C / Don’t Reload
/
MPC556
Reset
6-9, the range is determined by the value SWTC field. The value held in the
Waiting for 0x556C
Figure 6-8 SWT Interrupts and Exceptions
SYSTEM CONFIGURATION AND PROTECTION
State 0
Rev. 15 October 2000
0x556C / Don’t Reload
0xAA39 / Reload
Not 0xAA39 / Don’t Reload
Waiting for 0xAA39
Not 0x556C / Don’t Reload
State 1
MOTOROLA
6-17