MOTOROLA
TIMER/RESET MODULE
MMC2001
9-6
REFERENCE MANUAL
This bit controls the alarm interrupt function
0 =
AIF is inhibited from reaching the CPU
1 =
AIF is allowed to request an interrupt
AIF — Alarm Interrupt Flag
This read-only bit is the alarm interrupt flag. It is cleared by writing to the TOD alarm
fraction register (TODFAR).
0 =
No alarm interrupt is present
1 =
Alarm interrupt is present
9.4.4 TOD Seconds Register (TODSR)
The time-of-day seconds register is a 32-bit read/write register that holds the number
of elapsed seconds. It is clocked by a 1-Hz signal generated as a carry from the TOD
fraction register. When TODSR is read, the content of the fraction counter is latched
into a holding buffer to be read later. This prevents a fraction rollover between reads
of the two registers from causing incorrect data to be read. When TODSR is written,
the TODFR is cleared to all zeros. TODSR is not affected by the watchdog reset or by
a reset initiated by the external reset signal, but is undefined after a POR.
Access this register with 32-bit loads and stores only.
Figure 9-5 TOD Seconds Register
9.4.5 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.
TODSR — Time-of-Day Seconds Register
10001008
31
0
R
TOD SECONDS REGISTER
W
RESET:
Undefined on POR
Freescale Semiconductor,
I
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
nc.
..