🔌 Echelon 83331, 83332 MEP Sniffer with ESP32

A project for reading raw data from the MEP port of the Echelon 83331 electricity meter using an ESP32. Data is read in RAW format for later parsing and decryption with a locally stored encryption key.

🎯 Purpose

• Read measurement data directly from the meter's MEP port.
• Avoid dependencies like SaveEye, cloud services, or MQTT.
• Store and parse all data 100% locally.
• Later send data to Home Assistant via REST API.

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🔌 Hardware Connection

📟 Components

• ESP32 DevKit (WROOM recommended)
• RJ12 female socket or MEP adapter
• Optional logic level shifter (if MEP port uses RS-232 instead of TTL)
• Jumper wires

⚙️ MEP RJ12 Pinout (standard):

Pin	Signal	Example ESP32 GPIO
1	GND	GND
2	VCC (3.3/5V)	3.3V / 5V (check meter specs)
3	TX from meter	GPIO16 (RX)
4	RX to meter	GPIO17 (TX)
5–6	Not used	–

⚠️ Double-check voltage and signal type – if RS-232 is used, insert a MAX3232 between ESP32 and the meter.

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📊 Expected Data Output

Once decoding is active and the correct encryption key is implemented, the following output is expected from the meter:

Field	Unit	Description
meterType	String	Meter type (e.g., "MEP meter")
meterSerialNumber	String	Serial number of the meter
wifiRssi	dBm	Signal strength (only relevant for WiFi)
activeActualConsumption	Watt (W)	Instantaneous active consumption
activeActualProduction	Watt (W)	Instantaneous production (e.g., solar)
activeTotalConsumption	Wh/kWh	Accumulated consumption
activeTotalProduction	Wh/kWh	Accumulated production
reactiveActualConsumption	VAr	Instantaneous reactive consumption
reactiveActualProduction	VAr	Instantaneous reactive production
rmsVoltage (L1–L3)	Volt (V)	RMS voltage per phase
rmsCurrent (L1–L3)	mA / A	RMS current per phase
powerFactor	%	Power factor (e.g., 98 = 0.98 cos(φ))

Note: Some values depend on the meter's firmware and configuration.

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🔍 ESP32 Sniffer Code (Arduino C++)

Use this code to log raw data from the meter in HEX format for analysis:

#include <HardwareSerial.h>

HardwareSerial MEP(2);  // UART2

void setup() {
  Serial.begin(115200);
  MEP.begin(9600, SERIAL_8N1, 16, 17); // RX=GPIO16, TX=GPIO17

  Serial.println("🔍 Starting MEP sniffer...");
}

void loop() {
  while (MEP.available()) {
    byte b = MEP.read();
    if (b < 0x10) Serial.print("0");
    Serial.print(b, HEX);
    Serial.print(" ");
  }
}

👉 Once connected and receiving data, bytes will appear in the Serial Monitor (baud: 115200).

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🔐 Encryption Key

The project will later use the meter’s private encryption key (if required) to:

• Authenticate with the meter
• Decrypt binary data into readable values

🔒 Security Measures

• The key will be hardcoded in firmware.
• Changes require OTA or physical update – no access via web or serial interface.
• Key usage will be handled in a dedicated parsing section.

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🧪 Next Steps

1. Use this sniffer to log a data dump from the meter.
2. Compare values with your known usage/voltage to identify structure.
3. We will implement parsing + decryption, and REST push to Home Assistant.

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📬 Contact

Developed and maintained by Thomas Emil.
For technical questions, reach out via GitHub Issues or ESP32 RF-beams 💡