UM0402 datasheet(22/35 Pages) STMICROELECTRONICS

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Multi-tariff meter operation

UM0402

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5.2

Operation during power failure

During a normal operating mode the meter is supplied with the line voltage, the

microcontroller is in Run Mode and all devices are powered on.

If a power down occurs the meter is supplied by 4.8 V battery. In this case, the micro moves

to HALT mode and LCD, EEPROM and STPM14 are switched off.

As the micro senses the voltage going down, and before moving to HALT mode, it saves in

EEPROM all data.

5.2.1

Tamper mode

During power failure, the STPM14 metering device is switched off. Then line tamper is not

available, but box tamper is still recognized by the meter.

The behavior of the meter is the same of that during power up, as described in

Section 5.1.1: Tamper mode on page 18.

5.2.2

IR Mode

The functioning of IrDA module during power down is the same of that described above,

except that it is necessary, to wake up the micro from HALT mode, to send a specific

command.

5.2.3

LCD Display

During power down LCD is normally switched off. When the push button is pressed, micro

wakes up and the LCD displays the information listed above.

Once the push button has been pressed, if it is not pressed in 30 seconds the micro returns

to halt mode and the LCD is switched off again.

5.3

LCD icons description

The LCD can display different icons, which meaning is shown below.

Table 10.

LCD AMD Information

Screen n.

Data

Format

Icon

Meaning

149+j*3

Absolute

maximum demand

00000.000

PPower

Measure Unit

150+j*3

Date of

occurrence

dd.mm.yy

151+j*3

Time of

occurrence

hh.mm.ss

Min

Time indicator

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