MCP3909-I/SS Microchip Technology, MCP3909-I/SS Datasheet - Page 51

• Manufacturer Part Number: MCP3909-I/SS
• Description: IC POWER METERING-1 PHASE 24SSOP
• Manufacturer: Microchip Technology

Specifications of MCP3909-I/SS

• Package / Case: 24-SSOP (0.200", 5.30mm Width)
• Input Impedance: 390 KOhm
• Measurement Error: 0.1%
• Voltage - I/o High: 2.4V
• Voltage - I/o Low: 0.85V
• Current - Supply: 2.3mA
• Voltage - Supply: 4.5 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Meter Type: Single Phase
• Operating Temperature Range: - 40 C to + 85 C
• Mounting Style: SMD/SMT
• Supply Voltage Range: 4.5V To 5.5V
• Digital Ic Case Style: SSOP
• No. Of Pins: 24
• Interface Type: Serial, SPI
• Supply Voltage Max: 5.5V
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: MCP3909EV-MCU16 - EVALUATION BOARD FOR MCP3909MCP3909RD-3PH1 - REF DESIGN MCP3909 3PH ENGY MTR
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

6.1
© 2009 Microchip Technology Inc.
INTRODUCTION
Chapter 6. Meter Communications Protocol
The UART interface is used to communicate with the upper computer (MCU or PC). Via
the UART interface, the upper computer reads the measured parameters of the power
grid, and may also send system parameters and calibration parameters to target board
as well.
The communication interface is a bidirectional interface based on UART, using
master/slave half-duplex mode. The baud rate is 19,200 bps, with 1 start bit, 8 data bits
and 1 stop bit. Communication is done by frames with non-fixed-length frame structure,
definition of which is shonw in Table 6-1. Communication protocol is specified in
master-slave structure. The system in this design is the slave, and the upper computer
is the master. The master sends commands to the slave, and the slave responds to the
master.
UART communication uses half-duplex mode. The data format is 8-1-1 and the rate is
19,200 bps. The PC is the host computer, and the target board is the slave.
There are 14 command strings that the meter uses. These command strings are
defined in Table 6-1
TABLE 6-1:
Test Connection
Total Data Request
Harmonic Content, Phase A
Harmonic Content, Phase B
Harmonic Content, Phase C
Total Harmonic Distortion
Energy
Stop Energy Measurement and Clear Energy Values
Harmonic Power
Write Calibration Values to Meter
Write Phase Lag Calibration Values to Meter
Write Power Calibration Values to Meter
Write Energy Pulse Configuration - Active/Apparent
Reset All Calibration Values
Write Energy Pulse Constant
ENERGY METER REFERENCE DESIGN
COMMAND STRINGS
MCP3909 / DSPIC33F 3-PHASE
Command Description
DS51723A-page 51
Command
0x41
0x42
0x43
0x44
0x45
0x46
0x47
0x48
0x49
0x62
0x63
0x64
0x65
0x66
0x67