MOTOROLA
PROGRAMMING REFERENCE
MMC2001
C-8
REFERENCE MANUAL
Figure C-8 TOD Seconds Register
C.3.4 TOD Fraction Register (TODFR)
The 32-bit time-of-day fraction register holds eight bits of data that represent the
binary fraction of a second. It is clocked by the 32.768-kHz LOW_REFCLK divided by
128 (256 Hz). Reads of this register return the value latched when the TOD seconds
register was previously read. Continuous reads return the same value until the
TODSR is read and new data is latched from the fraction counter. These eight bits are
cleared whenever the TODSR is written but are not affected by either reset pin or the
watchdog reset conditions. The fraction counter is undefined after a POR. Writes to
this register cause all eight bits to be set.
Access this register with 32-bit accesses only.
Figure C-9 TOD Fraction Register
C.3.5 TOD Seconds Alarm Register (TODSAR)
The time-of-day seconds alarm register is a 32-bit read/write register which holds
data (in seconds) to be compared to the TOD seconds register. The comparison is
made every 1/256 of a second if the alarm function is enabled by the AE bit in the
TODCSR. Writes to this register inhibit alarm compares until the TODFAR is written.
For proper alarm operation, the fraction alarm register must be (re)written after a
write to this register. This register is not affected by any of the reset conditions.
Access this register with 32-bit loads and stores only.
TODSR — Time-of-Day Seconds Register
10001008
31
0
R
TOD SECONDS REGISTER
W
RESET:
Undefined on POR
TODFR — TOD Fraction Register
1000100C
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
R
TOD FRACTION REGISTER
0
0
0
0
0
0
0
0
W
Set to ones
RESET:
Undefined on POR
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
0
0
0
0
0
0
W
RESET:
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