© Koninklijke Philips Electronics N.V. 2006. All rights reserved.
User manual
Rev. 01 — 12 January 2006
216
Philips Semiconductors
UM10161
Volume 1
Chapter 17: RTC
17.4.4 Clock
Tick
Counter
Register (CTC - 0xE002 4004)
The Clock Tick Counter is read only. It can be reset to zero through the Clock Control
Register (CCR). The CTC consists of the bits of the clock divider counter.
17.4.5 Clock Control Register (CCR - 0xE002 4008)
The clock register is a 5-bit register that controls the operation of the clock divide circuit.
Each bit of the clock register is described in
17.4.6 Counter Increment Interrupt Register (CIIR - 0xE002 400C)
The Counter Increment Interrupt Register (CIIR) gives the ability to generate an interrupt
every time a counter is incremented. This interrupt remains valid until cleared by writing a
one to bit zero of the Interrupt Location Register (ILR[0]).
Table 186: Interrupt Location Register (ILR - address 0xE002 4000) bit description
Bit
Symbol
Description
Reset
value
0
RTCCIF
When one, the Counter Increment Interrupt block generated an interrupt.
Writing a one to this bit location clears the counter increment interrupt.
NA
1
RTCALF
When one, the alarm registers generated an interrupt. Writing a one to
this bit location clears the alarm interrupt.
NA
7:2
-
Reserved, user software should not write ones to reserved bits. The
value read from a reserved bit is not defined.
NA
Table 187: Clock Tick Counter Register (CTC - address 0xE002 4004) bit description
Bit
Symbol
Description
Reset
value
14:0
Clock Tick
Counter
Prior to the Seconds counter, the CTC counts 32,768 clocks per
second. Due to the RTC Prescaler, these 32,768 time increments may
not all be of the same duration. Refer to the
clock divider (prescaler)” on page 220
for details.
NA
15
-
Reserved, user software should not write ones to reserved bits. The
value read from a reserved bit is not defined.
NA
Table 188: Clock Control Register (CCR - address 0xE002 4008) bit description
Bit
Symbol
Description
Reset
value
0
CLKEN
Clock Enable. When this bit is a one the time counters are enabled.
When it is a zero, they are disabled so that they may be initialized.
NA
1
CTCRST
CTC Reset. When one, the elements in the Clock Tick Counter are
reset. The elements remain reset until CCR[1] is changed to zero.
NA
3:2
CTTEST
Test Enable. These bits should always be zero during normal
operation.
NA
4
CLKSRC
If this bit is 0, the Clock Tick Counter takes its clock from the Prescaler,
as on earlier devices in the Philips Embedded ARM family. If this bit is
1, the CTC takes its clock from the 32 kHz oscillator that’s connected to
the RTCX1 and RTCX2 pins (see
Section 17.7 “RTC external 32 kHz
oscillator component selection”
for hardware details).
NA
7:5
-
Reserved, user software should not write ones to reserved bits. The
value read from a reserved bit is not defined.
NA