Motorola MPC533 Reference Manual page 258

Memory Map and Register Definitions
Table 6-18. TBSCR Bit Descriptions (continued)
Bits Name
14 TBF Time base freeze. If this bit is set, the time base and decrementer stop while FREEZE is
asserted.
15 TBE Time base enable
0 Time base and decrementer are disabled
1 Time base and decrementer are enabled
6.2.2.4.5 Real-Time Clock Status and Control Register (RTCSC)
The RTCSC enables the different RTC functions and reports the source of the interrupts.
The register can be read anytime. A status bit is cleared by writing a one to it. (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 by default. Unlocking is accomplished by writing
0x55CCAA33 to its associated key register. See Section 8.8.3.2, "Keep-Alive Power
Registers Lock Mechanism."
MSB 1
0
Field
PORESET
Addr
Figure 6-35. Real-Time Clock Status and Control Register (RTCSC)
Bits Name
0:7 RTCIRQ Real-time clock interrupt request. Thee bits determine the interrupt priority level of the RTC. Refer
to Section 6.1.4, "Enhanced Interrupt Controller" for interrupt level encoding.
8 SEC Once per second interrupt. This status bit is set every second. It should be cleared by the
software.
9 ALR Alarm interrupt. This status bit is set when the value of the RTC equals the value programmed in
the alarm register.
10 — Reserved
11 4M Real-time clock source
0 RTC assumes that it is driven by 20 MHz to generate the seconds pulse.
1 RTC assumes that it is driven by 4 MHz
12 SIE Second interrupt enable. If this bit is set, the RTC generates an interrupt when the SEC bit is set.
13 ALE Alarm interrupt enable. If this bit is set, the RTC generates an interrupt when the ALR bit is set.
14 RTF Real-time clock freeze. If this bit is set, the RTC stops while FREEZE is asserted.
15 RTE Real-time clock enable
0 RTC is disabled
1 RTC is enabled
6-44
PRELIMINARY—SUBJECT TO CHANGE WITHOUT NOTICE
2 3 4 5 6
RTCIRQ
0000_0000_000
Table 6-19. RTCSC Bit Descriptions
MPC533 Reference Manual
Description
7 8 9 10
SEC ALR —
0x2F C220
Description
11 12 13 14
4M SIE ALE RTF
U 000
MOTOROLA
LSB
15
RTE
U