MCP3909RD-3PH3 Microchip Technology, MCP3909RD-3PH3 Datasheet - Page 41

• Manufacturer Part Number: MCP3909RD-3PH3
• Description: REF DESIGN FOR MCP3909 W/18F2520
• Manufacturer: Microchip Technology

Specifications of MCP3909RD-3PH3

• Main Purpose: Power Management, Energy/Power Meter
• Utilized Ic / Part: MCP3909, PIC18F2520, PIC18F4550
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Secondary Attributes: -
• Embedded: -
• Primary Attributes: -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

4.1
© 2008 Microchip Technology Inc.
PIC18F2520 PROTOCOL
Chapter 4. Meter Protocol and Timings
The RS-232 port of the PIC18F2520 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.
The last data byte is always an 'X' character. All commands will result in the same com-
mand being returned. The exception is the 'R' (read) command which will return addi-
tional 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.
• 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)
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
METER REFERENCE DESIGN
MCP3909 3-PHASE ENERGY
DS51643B-page 37