MPC555
/
MPC556
CLOCKS AND POWER CONTROL
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
8-24
CAL, and RTCSC. All other registers are unlocked. Each key has an address associ-
ated with it in the internal memory map.
A write of 0x55CCAA33 to the associated key register changes the key to the open
state. A write of any other data to this location changes the key to the locked state.
NOTE
A read of a key register may be interpreted as a write of a lock value
and may lock the associated KAPWR register.
The key registers are write-only. A read of the key register has undefined side effects
and may be interpreted as a write that locks the associated register.
lists the registers powered by KAPWR and the associated key registers.
Table 8-8 KAPWR Registers and Key Registers
KAPWR Register
Associated Key Register
Address or
SPR Number
Register
Address
Register
0x2F C200
Time Base Status and Control (TBSCR)
See
for bit descriptions.
0x2F C300
Time Base Status and Control Key
(TBSCRK)
0x2F C204
Time Base Reference 0 (TBREF0)
See
6.13.4.3 Time Base Reference Reg-
for bit descriptions.
0x2F C304
Time Base Reference 0 Key (TBREF0K)
0x2F C208
Time Base Reference 1 (TBREF1)
See
6.13.4.3 Time Base Reference Reg-
for bit descriptions.
0x2F C308
Time Base Reference 1 Key (TBREF1K)
0x2F C220
Real Time Clock Status and Control
(RTCSC)
See
for bit descriptions.
0x2F C320
Real Time Clock Status and Control Key
(RTCSCK)
0x2F C224
Real Time Clock (RTC)
See
6.13.4.6 Real-Time Clock Register
0x2F C324
Real Time Clock Key (RTCK)
0x2F C228
Real Time Alarm Seconds (RTSEC)
Reserved
0x2F C328
Real Time Alarm Seconds Key (RTSECK)
0x2F C22C
Real Time Alarm (RTCAL)
See
6.13.4.7 Real-Time Clock Alarm
for bit descriptions.
0x2F C32C
Real Time Alarm Key (RTCALK)
0x2F C240
PIT Status and Control (PISCR)
See
for bit descriptions.
0x2F C340
PIT Status and Control Key (PISCRK)
0x2F C244
PIT Count (PITC)
See
for bit descriptions.
0x2F C344
PIT Count Key (PITCK)
0x2F C280
System Clock Control Register (SCCR)
See
0x2F C380
System Clock Control Key (SCCRK)
0x2F C284
PLL Low-Power and Reset-Control
Register (PLPRCR)
See
for bit descriptions.
0x2F C384
PLL Low-Power and Reset-Control Regis-
ter Key (PLPRCRK)
0x2F C288
Reset Status Register (RSR)
See
0x2F C388
Reset Status Register Key (RSRK)
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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