MPC555
/
MPC556
SYSTEM CONFIGURATION AND PROTECTION
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
6-32
6.13.4.5 Real-Time Clock Status and Control Register
The RTCSC is used to enable the different RTC functions and to report the source of
the interrupts. The register can be read anytime. A status bit is cleared by writing it to
a one. (Writing a zero does not affect a status bit’s value.) More than one status bit can
be cleared at a time. This register is locked after RESET. Unlocking is accomplished
by writing 0x55CCAA33 to its associated key register. See
TBSCR
— Time Base Control and Status Register
0x2F C200
MSB
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
LSB
15
TBIRQ
REFA
REFB
RESERVED
REFAE REFBE
TBF
TBE
PORESET:
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Table 6-16 TBSCR Bit Descriptions
Bit(s)
Name
Description
0:7
TBIRQ
Time base interrupt request. These bits determine the interrupt priority level of the time base. Re-
fer to
for interrupt level encodings.
8
REFA
Reference A (TBREF0) interrupt status.
0 = No match detected
1 = TBREF0 value matches value in TBL
9
REFB
Reference B (TBREF1) interupt status.
0 = No match detected
1 = TBREF1 value matches value in TBL
10:11
—
Reserved
12
REFAE
Reference A (TBREF0) interrupt enable. If this bit is set, the time base generates an interrupt
when the REFA bit is set.
13
REFBE
Reference B (TBREF1) interrupt enable. If this bit is set, the time base generates an interrupt
when the REFB bit is set.
14
TBF
Time base freeze. If this bit is set, the time base and decrementer stop while FREEZE is assert-
ed.
15
TBE
Time base enable
0 = Time base and decrementer are disabled
1 = Time base and decrementer are enabled
RTCSC
— Real-Time Clock Status and Control Register
0x2F C220
MSB
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
LSB
15
RTCIRQ
SEC
ALR
Re-
served
4M
SIE
ALE
RTF
RTE
RESET:
0
0
0
0
0
0
0
0
0
0
0
—
0
0
0
—
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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