Maxim Integrated 78M6612 M-API Library - Manual (Page 5)

UG_6612_036 78M6612 M-API Library User Guide
Rev. 1.00 5
1 Introduction
This document describes the Metrology Application Programming Interface (M-API) version 2.00 firmware
libraries available from Teridian for use with the 78M6612 IC. These libraries are specifically designed for
measurement and switch control of two (2) single-phase AC outlets (same phase).
The firmware delivery is a set of metrology libraries that configure and operate the measurement front
end (e.g. MUX, ADC, CE, etc.) and provides simplified access to measurement output data such as
Power, Voltage, Current, accumulated Energy and Line Frequency. All measurement calculations are
computed by the MAPI library every accumulation interval and mapped to a dedicated block of registers
reserved by the library.
Measurement data are made available to the user application via API calls. A demo application making
use of the M-API library set and serial UART interface is included as part of the 78M6612 OMU
Evaluation Kit.
Timer functions using the hardware RTC are also available and can be accessed directly by the
application. APIs specific to RTC are not available in the current library. Contact a Teridian
representative for more information on non-Volatile RTC operation (e.g. battery backup modes).
1.1 Terminology
The following terminology is used throughout this document:
•
CREEP – Threshold value where measurement outputs are squelched to zero.
•
IMAX – External RMS current corresponding to 250 mVpk at the current input of the 78M6612. It should be set
IMAX= (Vpk/
√2)/R
SENSE
.
•
VARs – Reactive Power (Q)
•
VAs – Apparent Power (S).
•
Watts – Active Power (P).
•
VMAX – External RMS voltage corresponding to 250 mVpk at the voltage input of the 78M6612 (VA, VB). It
must be set high enough to account for over-voltages.
•
NB – Narrowband values.
•
WB – Wideband values.