MCP3909RD-1PH1 Microchip Technology, MCP3909RD-1PH1 Datasheet - Page 31

• Manufacturer Part Number: MCP3909RD-1PH1
• Description: BOARD DES MCP3909 ENERGY METER
• Manufacturer: Microchip Technology

Specifications of MCP3909RD-1PH1

• Main Purpose: Power Management, Energy/Power Meter
• Embedded: Yes, MCU, 8-Bit
• Utilized Ic / Part: MCP3909, PIC18F85J90
• Primary Attributes: Single Phase Shunt Energy Meter
• Secondary Attributes: 16 Bit ADC
• Ic Function: Single Phase Energy Measurement IC
• Supply Voltage Range: 4.5V To 5.5V
• Operating Temperature Range: -40°C To +85°C
• Digital Ic Case Style: SSOP
• No. Of Pins: 24
• Interface Type: SPI
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

4.1
© 2009 Microchip Technology Inc.
PIC18F85J90 PROTOCOL
Chapter 4. Meter Protocol and Timings
The RS-232 port of the PIC18F85J90 is used to access the register map of the meter.
In addition to reading and writing of registers, there are also dedicated commands for
clearing calibration registers, loading calibration registers, and storing calibration
registers to flash. The first byte RS-232 data is an ASCII character that represents the
command, and each command has a specific protocol. Each command ends with the
ASCII character “X”.
4.1.1
The first byte of the data (byte 0) is an ASCII character E, L, S, W and R.
• E - Echo All Data Received (ECHO)
• L - Load Calibration Registers from Flash (LOAD)
• S - Store Calibration Registers (STORE)
• W - Write Bytes (WRITE)
• R - Read Bytes (READ)
The last data byte is always an 'X' character. All commands will result in the same
command being returned. The exception is the 'R' (read) command which will return
additional data in lieu of the number of bytes.
4.1.1.1
4.1.1.2
This command is used to verify that the calibration values were actually written into
flash (or EEPROM). Once the software executes a 'SX' command, it should verify that
the values were stored by issuing an 'LX' command and then reading the calibration
values with a 'R' command.
4.1.1.3
Note that the store command will write all calibration values to internal EEPROM and
this function takes some time. During that time, the meter is not functional. The store
command should only be used after calibrating the meter and not while it is in actual
use.
Example: 'EABCDEFGHIJKLMNOPQRSTUVWYZ1234567890X'.
Returns: 'EABCDEFGHIJKLMNOPQRSTUVWYZ1234567890X'.
Example: 'LX'.
Returns: 'LX'.
Example: 'SX'.
Returns: 'SX'.
Command Description
“E” ECHO: - ECHO ALL DATA RECEIVED
“L” LOAD: LOAD CALIBRATION REGISTERS FROM FLASH.
“S” STORE: STORE CALIBRATION REGISTERS INTO FLASH
MCP3909/PIC18F85J90 SINGLE PHASE
ENERGY METER REFERENCE DESIGN
DS51884A-page 31