C161RI_1 Datasheet, PDF (220/317 Pages) Siemens Semiconductor Group – 16-Bit CMOS Single-Chip Microcontroller

The Real Time Clock
C161RI
14 The Real Time Clock
The Real Time Clock (RTC) module of the C161RI basically is an independent timer chain which is
clocked directly with the oscillator clock and serves for different purposes:
q System clock to determine the current time and date
q Cyclic time based interrupt
q 48-bit timer for long term measurements
Control Registers
Data Registers
Counter Registers
Interrupt Control
SYSCON2 E
T14REL E
T14
E
RTCH
E
RTCL
E
ISNC
E
XP3IC E
SYSCON2 Power Management Control Register
T14REL Timer T14 Reload Register
T14
Timer T14 Count Register
Figure 14-1
SFRs Associated with the RTC Module
RTCH
RTCL
ISNC
XP3IC
Real Time Clock Register, High Word
Real Time Clock Register, Low Word
Interrupt Subnode Control Register
RTC Interrupt Control Register
The RTC module consists of a chain of 3 divider blocks, a fixed 8:1 divider, the reloadable 16-bit
timer T14 and the 32-bit RTC timer (accessible via registers RTCH and RTCL). Both timers count
up.
The clock signal for the RTC module is directly derived from the on-chip oscillator frequency (not
from the CPU clock) and fed through a separate clock driver. It is therefore independent from the
selected clock generation mode of the C161RI and is controlled by the clock generation circuitry.
RTC Register Location within the ESFR Space
Register Name Long/Short Address Reset Value Notes
T14
F0D2_H / 69_H
UUUU_H
Prescaler timer, generates input clock for
RTC register and periodic interrupt
T14REL
RTCH
RTCL
F0D0_H / 68_H
F0D6_H / 6B_H
F0D4_H / 6A_H
UUUU_H
UUUU_H
UUUU_H
Timer reload register
High word of RTC register
Low word of RTC register
Note: The RTC registers are not affected by a reset. After a power on reset, however, they are
undefined.
Semiconductor Group
14-1
1998-06-01