AN2549 datasheet(11/33 Pages) STMICROELECTRONICS

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AN2549

Modified features

11/33

The handling of the RTCAIR and RTCSIR flags (bits 2 and 0 of the RTCCON register,

respectively) has also changed:

●

In the ST10F272Z2, these flags are cleared by writing them to ‘1’

●

In the ST10F269Zx, these flags are cleared by writing them to ‘0’

As these flags must be cleared by software when entering the corresponding interrupt

service routine, a change in the application code is needed.

Example for RTCSIR flag

Replace ST10F269Zx code:

RTCCON &= 0xFFFE;// Clear RTCSIR flag

Reserved

OFF

OSC

RTC

OFF

Reserved

RTC

AEN

RTC

AIR

RTC

SEN

RTC

SIR

-R/W

R/W

Table 9.

RTCCON register description

Bit

Function

Reset

value

RTCSIR

RTC Second Interrupt Request flag (every basic clock unit)

0: The bit was reset less than a Basic Clock unit ago.

1: The interrupt was triggered.

RTCSEN

RTC Second Interrupt Enable

0: RTC_SecIT is disabled.

1: RTC_SecIT is enabled; it is generated every basic clock unit.

RTCAIR

RTC Alarm Interrupt Request flag (when the alarm is triggered)

0: The bit was reset less than n Basic Clock units ago.

1: The interrupt was triggered.

RTCAEN

RTC Alarm Interrupt Enable

0: RTC_alarmIT is disabled.

1: RTC_alarmIT is enabled.

RTCOFF

RTC Switch Off bit

0: Clock oscillator and RTC keep on running even if ST10 is in Power Down

mode.

1: Clock oscillator is switched off when ST10 enters Power Down mode.

Additionally, when setting this bit, RTC dividers and counters are stopped

and registers can be written.

OSC

Oscillator Selection Flag

0: The clock oscillator used by the RTC is the main oscillator.

1: The clock oscillator used by the RTC is the low power 32 kHz oscillator.

OFF32

32 kHz Oscillator Switch Off bit

0: The 32 kHz oscillator is enabled. The RTC is clocked with 32 kHz if there

is a valid signal.

1: The 32 kHz oscillator is disabled. The RTC is clocked by the main

oscillator.

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