XC164-16 Datasheet, PDF (71/417 Pages) Infineon Technologies AG – 16-Bit Single-Chip Microcontroller with C166SV2 Core Volume 2 (of 2): Peripheral Units

XC164-16 Derivatives
Peripheral Units (Vol. 2 of 2)
Real Time Clock
15.1
Defining the RTC Time Base
The timer chain of the RTC is clocked with the count clock signal f_RTC which is derived
from the prescaled main oscillator (see Figure 15-2 and Figure 15-3). Optionally
prescaled by a factor of 8, this is the basic RTC clock. Depending on the operating mode,
timer T14 may provide the count increments used by the application and thus determine
the input frequency of the RTC timer, that is, the RTC time base (see also Table 15-3).
The RTC is also supplied with the system clock f_SYS of the XC164. This clock signal is
used to control the RTC’s logic blocks and its bus interface. To synchronize properly to
the count clock, the system clock must run at least four times faster than the count clock,
this means f_SYS ≥ 4 × f_CNT.
f_RTC
>1
RUN
8:1
1 _{MUX fCNT}
0
RTC
Count
Clock
PRE
Main
f
OSCm
OSC
32:1
f_SYS
Clock
Generation
Unit
Async Mode 1
MUX
Sync Mode 0
RTC
Module
Clock
RTCCM
SYSCON0.14
MCB05413_X4
Figure 15-2 RTC Clock Supply Block Diagram
For an example, Table 15-1 lists the interrupt period range and the T14 reload values
(for a time base of 1 s and 1 ms):
Table 15-1 RTC Time Base Examples
Oscillator
T14 Intr. Period
Frequency _Min.
Max.
Reload Value A
T14REL Base
4 MHz
8.0 µs
4.194 s
------_H/
C2F7_H
1.000 s
Reload Value B
T14REL Base
FF83_H/
FFF0_H
1.000 ms/
1.024 ms
Note: Select one value from the reload value pairs, depending if the 8:1 prescaler is
disabled/enabled.
User’s Manual
RTC_X41, V2.1
15-2
V2.1, 2004-03