UM1529 Datasheet, PDF (12/35 Pages) STMicroelectronics – This document describes the functioning

Hardware details
5
Hardware details
UM1529
5.1
5.1.1
Metering IC U1
The programmable single-phase energy metering IC STPM10BTR (package: TSSOP20) is
interfaced to the microcontroller using a three-wire SPI interface. Active energy, apparent
energy, instantaneous voltage, instantaneous current values are obtained from the STPM10
metering IC. For calibration of the STPM10, auto-calibration is implemented.
Clocking Y1
A 4.194 MHz crystal is used as clock generator input for the metering IC.
For more details about auto-calibration, please refer to Section 6.1: Auto-calibration mode.
5.2
5.2.1
5.2.2
5.2.3
5.2.4
Microcontroller U2
The microcontroller STM8L152C6T6 (package: LQFP48, 32 K Flash, 2 KB RAM, 48-pin) is
responsible for all the data management and power management tasks. MCU consumes
much lower power and has in-built RTC for date and time management.
LED D10
LED D10 is the pulse-out LED for cumulative energy. This is used for testing energy meter
energy calculation accuracy.
Switch SW1, SW2
Switch SW1 is the reset switch for the microcontroller.
Switch SW2 is the case tamper switch. This is used to detect case tampering of the energy
meter solution. For more details, refer to Section 6.4: LCD display modes.
Jumper J2
Table 1. 3-pin jumper header
Jumper
Close: 1-2
Close: 2-3
Microcontroller pin PA1 Microcontroller pin PA1
J2
is connected to reset is connected to LED
switch SW1.
D10.
Default
Close: 2-3
Clocking Y2
A 32.768 kHz crystal is used as clock input for LSE (low speed external) for the
microcontroller RTC block. The microcontroller core is clocked by HSI (high speed internal)
clock.
12/35
Doc ID 022953 Rev 1