C167CS datasheet(308/517 Pages) INFINEON

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C167CS

Derivatives

The Real Time Clock

User’s Manual

14-2

V2.0, 2000-07

Figure 14-2

RTC Block Diagram

System Clock Operation

A real time system clock can be maintained that keeps on running also during idle mode

and power down mode (optionally) and represents the current time and date. This is

possible as the RTC module is not effected by a reset.

The maximum resolution (minimum stepwidth) for this clock information is determined

by timer T14’s input clock. The maximum usable timespan is achieved when T14REL is

loaded with 0000H and so T14 divides by 2

16.

Cyclic Interrupt Generation

The RTC module can generate an interrupt request whenever timer T14 overflows and is

reloaded. This interrupt request may e.g. be used to provide a system time tick

independent of the CPU frequency without loading the general purpose timers, or to wake

up regularly from idle mode. The interrupt cycle time can be adjusted via the timer T14

reload register T14REL. Please refer to “RTC Interrupt Generation” below for more details.

48-bit Timer Operation

The concatenation of the 16-bit reload timer T14 and the 32-bit RTC timer can be

regarded as a 48-bit timer which is clocked with the RTC input frequency divided by the

fixed prescaler. The reload register T14REL should be cleared to get a 48-bit binary

timer. However, any other reload value may be used.

The maximum usable timespan is 248 (

≈ 1014) T14 input clocks, which would equal more

than 100 years at an oscillator frequency of 20 MHz.

MCD04432

T14REL

T14

8:1

RTC

RTCL

RTCH

Interrupt

Request

Reload

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