UM0402 datasheet(5/35 Pages) STMICROELECTRONICS

5 / 35 page

UM0402

Overview

5/35

A 16 MHz crystal is used for obtaining an 8 MHz CPU clock for the micro.

This meter has SPI EEPROM (M95256) with 256 Kb of memory, and SPI RTC (M41T94) for

date and time functions. 3V rechargeable battery is used to supply RTC for when the line

power is down and the battery is fully discharged.

Figure 1.

Multi-tariff meter board

The board has a Viper12-based switching power supply. When line power is not available,

power to the application is supplied by 4.8V rechargeable battery.

An LCD display is present with 24x4 segments, customized for electricity meter use.

This board also supports IRDA protocol IEC62056-21 mode C.

There are two 10-pin connectors, one to program STPM14 internal OTP registers, and one

for microcontroller ICP.

Two jumpers are used for the microcontroller reset and to simulate a box tamper. A push

button is used to display various parameters on the LCD display. 30 seconds after the switch

is pressed without further activity, the LCD screen once again displays the first screen

showing accumulated kWh and eventual error symbols. However, repeated presses of the

button cycle through the display of additional information.

See Table 8 on page 19 for full details on the parameters displayed on the LCD.

UM0402 Datasheet(PDF) 5 Page - STMicroelectronics