AN2159 Datasheet, PDF (1/23 Pages) STMicroelectronics – SPI protocol for STPM01/STPM10 metering devices

AN2159
Application note
SPI protocol for STPM01/STPM10 metering devices
Introduction
The STPM01 and STPM10 devices are energy meter ASSPs (Application Specific Standard
Products) designed to address a wide range of electricity metering requirements thanks to
their built-in functionalities as signal conditioning, signal processing, data conversion,
input/output signals and voltage reference.
STPM10 is dedicated for peripheral use only in microcontroller based applications, while
STPM01 is able to work as a peripheral but also as a standalone device, since it can
permanently store configuration and calibration data.
Both the devices have an SPI port to write configuration parameters and read all the
information on the line energy from their internal registers.
Measured data (like active, reactive and apparent energy, V_RMS, I_RMS, instantaneous
voltage and current, line frequency, device status etc.) should be read by the microcontroller
at a fixed time interval to be further processed.
This application note describes the SPI protocol to read measured data from STPM01 and
STPM10 in a single-phase energy meter and how these readings should be processed by
the application.
Figure 1. STPMxx based application block diagram
July 2010
Doc ID 11400 Rev 3
1/23
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