Maxim Integrated 78M6631 - Manual (Page 3)

UG_6631_078 78M6631 Firmware Description Document
Rev 2 3
Table of Contents
1 Introduction ................................................................................................................................... 5
2 Functional Description .................................................................................................................. 7
2.1 Initialization and Startup ........................................................................................................... 7
2.2 Measurements and Signal Processing Flow ............................................................................. 7
2.2.1 Description of Measurement Equations........................................................................ 7
2.2.2 Front-End and Input Stage .......................................................................................... 8
2.2.3 Voltage and Current RMS Calculation ......................................................................... 9
2.2.4 Active, Reactive and Apparent Power Calculation ...................................................... 10
2.2.5 Voltage and Current Harmonics and Fundamental Measurement............................... 11
2.2.6 Power Harmonics and Fundamental Measurement .................................................... 11
2.2.7 Power Factor Calculation ........................................................................................... 12
2.2.8 Line Frequency ......................................................................................................... 12
2.2.9 Accumulation Interval ................................................................................................ 12
2.2.10 Zero Crossing Detector ............................................................................................. 12
2.2.11 Sine and Cosine Reference ....................................................................................... 13
2.2.12 High-Pass Filters ....................................................................................................... 13
2.3 Configuration and Control ...................................................................................................... 14
2.3.1 Input Registers .......................................................................................................... 14
2.3.2 Sensors Configuration ............................................................................................... 14
2.3.3 Updating Flash .......................................................................................................... 14
2.3.4 Scaling ...................................................................................................................... 14
2.3.5 Calibration ................................................................................................................. 15
2.3.6 Phase Error Compensation........................................................................................ 16
2.3.7 Limit (Alarms) Settings .............................................................................................. 16
2.3.8 Creep Threshold........................................................................................................ 16
2.3.9 Digital I/O Configuration............................................................................................. 16
3 Serial Peripheral Interface (SPI) .................................................................................................. 17
4 Serial Communication and CLI ................................................................................................... 18
4.1 CLI Interface .......................................................................................................................... 18
5 Register Descriptions .................................................................................................................. 19
5.1 Command Register ................................................................................................................ 19
5.2 Status Register ...................................................................................................................... 20
5.3 Measurement Results Register .............................................................................................. 21
5.3.1 High-Rate Results Registers...................................................................................... 23
5.4 Parameters Configuration ...................................................................................................... 24
5.4.1 Scaling ...................................................................................................................... 24
5.4.2 Alarms Limit Setting................................................................................................... 24
5.4.3 Phase Error Compensation........................................................................................ 24
5.4.4 Digital I/O Configuration............................................................................................. 25
5.4.5 Calibration and Configuration Variables ..................................................................... 25
6 System Connection Diagram Examples ..................................................................................... 26
7 Command Line Interface (CLI) Description ................................................................................ 29
7.1 Identification and Information Commands............................................................................... 29
7.2 Reset Commands .................................................................................................................. 29
7.3 Data Access Commands ........................................................................................................ 29
7.3.1 Individual Address Read ............................................................................................ 30
7.3.2 Consecutive Read ..................................................................................................... 30
7.3.3 Block Reads .............................................................................................................. 30
7.3.4 Concatenated Reads ................................................................................................. 30
7.3.5 Repeat Command ..................................................................................................... 31
8 Contact Information ..................................................................................................................... 32
Revision History .................................................................................................................................. 32