XC161 Datasheet, PDF (80/419 Pages) Infineon Technologies AG – 16-Bit Single-Chip Microcontroller with C166SV2 Core Volume 2 (of 2): Peripheral Units

XC161 Derivatives
Peripheral Units (Vol. 2 of 2)
Real Time Clock
Each timer in the chain divides the clock by (2^{<timer_width>} - <reload_value>) : 1, as the
timers count up. Table 15-3 shows the reload values which must be chosen for a specific
scenario (i.e. operating mode of the RTC).
Table 15-3 Reload Value Scenarios
Formula
REL3
2¹⁰ - 24
REL2
2⁶ - 60
REL1
2⁶ - 60
REL0
2¹⁰ - 1000
T14REL
2¹⁶ - 33
Rel. Value
Function
Intr. Period
3E8_H
h
day
04_H
m
hour
04_H
s
minute
018_H
1/1000 s
second
FFDF_H
Prescaler
millisec.¹⁾
Formula
2¹⁰ - 7
2⁶ - 24
2⁶ - 60
2¹⁰ - 60
2¹⁶ - 32768
Rel. Value 3F9_H
28_H
04_H
3C4_H
Function day
h
m
s
8000_H
Prescaler
Intr. Period week
day
hour
minute
second
1) T14 errors in the first example (ms) can be compensated either by choosing an adapted value for REL0, or by
using software correction.
15.3.3 Cyclic Interrupt Generation
The RTC module can generate an interrupt request whenever one of the timers
overflows and is reloaded. This interrupt request may be used, for example, to provide
a system time tick independent of the CPU frequency without loading the general
purpose timers, or to wake up regularly from sleep mode. The interrupt cycle time can
be adjusted by choosing appropriate reload values and by enabling the appropriate
interrupt request.
In this mode, the other operating modes can be combined. For example, a reload value
of T14REL = F9C0_H (2¹⁶ - 1600) generates a T14 interrupt request every 50 ms to wake-
up the system regularly. Still the subsequent timers can be configured to represent the
time or build a binary counter, however with a different time base.
User’s Manual
RTC_X8, V2.1
15-11
V2.2, 2004-01