MCP3909RD-3PH1 Microchip Technology, MCP3909RD-3PH1 Datasheet - Page 28

• Manufacturer Part Number: MCP3909RD-3PH1
• Description: REF DESIGN MCP3909 3PH ENGY MTR
• Manufacturer: Microchip Technology

Specifications of MCP3909RD-3PH1

• Main Purpose: Power Management, Energy/Power Meter
• Embedded: No
• Utilized Ic / Part: MCP3909, PIC18F2520, PIC18F4550
• Primary Attributes: 3-Ph, 220 VAC, In Case, LCD, USB, GUI
• Secondary Attributes: Opto-Isolated Interface for Safety
• Operating Voltage: 220 V
• Operating Current: 5 A
• Description/function: Energy Meter
• For Use With/related Products: MCP3909
• Lead Free Status / RoHS Status: Not applicable / Not applicable

MCP3909 / dsPIC33F 3-Phase Energy Meter Reference Design
DS51723A-page 28
After system power-up, the MCU enters the initialization process, which includes
proper configuration of the I/O ports and on-chip peripherals (such as timer, UART, SPI
and IC). At the same time, the system control parameters can be loaded from the
external EEPROM and variables are all initialized.
Since most tasks of this system are accomplished through interrupts, only three tasks
are carried out in the system main loop, which are interpreting/processing UART
communication protocol, calculating parameters, and detecting neutral current. The
UART communication is performed in function UART_process(), the executing
frequency of which depends on the polling frequency of the upper computer.
Parameters are calculated by the function Calculation(), which is executed once every
3 cycles of the power grid. Neutral current is detected by function ComputeNeutral-
Current(), and computing is performed once every 16 cycles of the power grid.
© 2009 Microchip Technology Inc.