© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
User manual
Rev. 01 — 15 August 2005
277
Philips Semiconductors
UM10139
Volume 1
Chapter 19: RTC
19.4.1 RTC
interrupts
Interrupt generation is controlled through the Interrupt Location Register (ILR), Counter
Increment Interrupt Register (CIIR), the alarm registers, and the Alarm Mask Register
(AMR). Interrupts are generated only by the transition into the interrupt state. The ILR
separately enables CIIR and AMR interrupts. Each bit in CIIR corresponds to one of the
time counters. If CIIR is enabled for a particular counter, then every time the counter is
incremented an interrupt is generated. The alarm registers allow the user to specify a date
and time for an interrupt to be generated. The AMR provides a mechanism to mask alarm
compares. If all nonmasked alarm registers match the value in their corresponding time
counter, then an interrupt is generated.
The RTC interrupt can bring the microcontroller out of power-down mode if the RTC is
operating from its own oscillator on the RTCX1-2 pins. When the RTC interrupt is enabled
for wakeup and its selected event occurs, XTAL1/2 pins associated oscillator wakeup
cycle is started. For details on the RTC based wakeup process see
“Interrupt Wakeup register (INTWAKE - 0xE01F C144)” on page 22
and
19.4.2 Miscellaneous register group
summarizes the registers located from 0 to 7 of A[6:2]. More detailed
descriptions follow.
19.4.3 Interrupt
Location
Register (ILR - 0xE002 4000)
The Interrupt Location Register is a 2-bit register that specifies which blocks are
generating an interrupt (see
). Writing a one to the appropriate bit clears the
corresponding interrupt. Writing a zero has no effect. This allows the programmer to read
this register and write back the same value to clear only the interrupt that is detected by
the read.
Table 264: Miscellaneous registers
Name
Size
Description
Access
Address
ILR
2
Interrupt Location. Reading this location
indicates the source of an interrupt. Writing a
one to the appropriate bit at this location clears
the associated interrupt.
R/W
0xE002 4000
CTC
15
Clock Tick Counter. Value from the clock
divider.
RO
0xE002 4004
CCR
4
Clock Control Register. Controls the function of
the clock divider.
R/W
0xE002 4008
CIIR
8
Counter Increment Interrupt. Selects which
counters will generate an interrupt when they
are incremented.
R/W
0xE002 400C
AMR
8
Alarm Mask Register. Controls which of the
alarm registers are masked.
R/W
0xE002 4010
CTIME0
32
Consolidated Time Register 0
RO
0xE002 4014
CTIME1
32
Consolidated Time Register 1
RO
0xE002 4018
CTIME2
32
Consolidated Time Register 2
RO
0xE002 401C