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Real-Time Clock
MCF52235 ColdFire® Integrated Microcontroller Reference Manual, Rev. 6
8-9
Freescale Semiconductor
8.2.8
RTC Stopwatch Minutes Register (STPWCH)
The stopwatch minutes (STPWCH) register contains the current stopwatch countdown value. When the
minute counter of the TOD clock increments, the value in this register decrements.
8.2.9
RTC Days Counter Register (DAYS)
The real-time clock days counter register (DAYS) is used to program the day for the TOD clock. When the
HOUR field of the HOURMIN register rolls over from 23 to 00, the day counter increments. It can be read
or written at any time. After a write, the time changes to the new value. This register cannot be reset
because the real-time clock is always enabled at reset. Only 16-bit accesses to this register are allowed.
IPSBAR
Offset: 0x03DC (STPWCH)
Access: User read/write
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
R
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
W
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
R
0
0
0
0
0
0
0
0
0
0
CNT
W
Reset
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
Figure 8-9. RTC Stopwatch Minutes Register (STPWCH)
Table 8-9. STPWCH Field Descriptions
Field
Description
31–6
Reserved, should be cleared.
5–0
CNT
Stopwatch count. This field contains the stopwatch countdown value.
Note: The stopwatch counter is decremented by the minute (MIN) tick output from the real-time clock, so the
average tolerance of the count is 0.5 minutes. For better accuracy, enable the stopwatch by polling the
MIN bit of the RTCISR register or by polling the minute interrupt service routine.
Because
of
an
order
from
the
United
States
International
Trade
Commission,
BGA-packaged
product
lines
and
part
numbers
indicated
here
currently
are
not
available
from
Freescale
for
import
or
sale
in
the
United
States
prior
to
September
2010:MCF52234CVM60,
MCF52235CVM60