XC167-16 Datasheet, PDF (72/442 Pages) Infineon Technologies AG – 16-Bit Single-Chip Microcontroller with C166SV2 Core Volume 2 (of 2): Peripheral Units

XC167-16 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 auxiliary oscillator or 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 XC167. 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.
Aux.
f
OSCa
OSC
>1
REFCLK
RUN
f
RTCa
f
RTCm
MUX f_RTC
8:1
1
0
MUX f_CNT
RTC
Count
Clock
PRE
Main ^fOSCm
OSC
32:1
f_SYS
Clock
Generation
Unit
Async Mode 1
MUX
Sync Mode 0
RTC
Module
Clock
RTCCM
SYSCON0.14
MCB05413
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
Oscillator
Frequency
32.768 kHz
RTC Time Base Examples
T14 Intr. Period
Reload Value A
Min.
Max. T14REL
Base
30.52 µs 16.0 s 8000_H/F000_H 1.000 s
Reload Value B
T14REL Base
FFDF_H/
FFFC_H
1.007 ms/
0.977 ms
Note: Select one value from the reload value pairs, depending if the 8:1 prescaler is
disabled/enabled.
User’s Manual
RTC_X8, V2.1
15-2
V2.0, 2004-04