EMT7110.cpp

#include "EMT7110.h"

// Data rate: 9.579 kbit/s

// Message-Format
// ---------------------------------------------------------------------------
// Byte  0 + 1        Identification normally: 25 6A  during Pairing: 25 2A
// Byte  2 + 3 	      ID
// Byte  4 Bit 6 	    Device connected
// Byte  4 Bit 7      Pairing flag
// Byte  4 Bit 0..5   Power 0.5 W steps
// Byte  5            Power 0.5 W steps
// Byte  6 + 7 	      Current (mA),
// Byte  8 	          Voltage (0.5 V steps - 128 V)
// Byte  9 Bit 6      ???
// Byte  9 Bit 7      ???
// Byte  9 Bit 0..5   Accumulated Power (0.01 kWh steps)
// Byte 10            Accumulated Power (0.01 kWh steps)
// Byte 11 	          CRC sum on all 12 bytes == 0

void EMT7110::DecodeFrame(byte *data, struct Frame *frame) {
  frame->IsValid = true;
  frame->Header1 = data[0];
  frame->Header2 = data[1];
  frame->PairingFlag = (data[4] & 0b10000000) > 0;
  frame->ID = (data[2] << 8) | data[3];
  frame->Byte9_6 = (data[9] & 0b01000000) > 0;
  frame->Byte9_7 = (data[9] & 0b10000000) > 0;

  if (frame->PairingFlag) {
    frame->Voltage = 0.0;
    frame->Current = 0.0;
    frame->Power = 0.0;
    frame->AccumulatedPower = 0.0;
    frame->ConsumersConnected = false;
    frame->CRC = 0;
    frame->IsValid = false;
  }
  else {
    frame->Voltage = 128.0 + data[8] * 0.5;
    frame->Current = (data[6] << 8) | data[7];
    frame->Power = ((data[4] & 0x3F) << 8 | data[5]) / 2;
    frame->AccumulatedPower = ((data[9] & 0x3F) << 8 | data[10]) / 100.0;
    frame->ConsumersConnected = (data[4] & 0b01000000) > 0;
    frame->CRC = data[11];
    frame->IsValid = CrcIsValid(data);
  }

}

bool EMT7110::DisplayFrame(byte *data, struct EMT7110::Frame &frame, bool fOnlyIfValid) {
  if (fOnlyIfValid && !frame.IsValid) {
	  return frame.IsValid;
  }

  // MilliSeconds
  static unsigned long lastMillis;
  unsigned long now = millis();
  char div[16];
  sprintf(div, "%06d ", now - lastMillis);
  lastMillis = millis();
  Serial.print(div);

  // Show the raw data bytes
  Serial.print("EMT7110 [");
  for (int i = 0; i < FRAME_LENGTH; i++) {
    Serial.print(data[i], HEX);
    Serial.print(" ");
  }
  Serial.print("]");

  // Check CRC
  if (!frame.IsValid) {
    Serial.print(" CRC:WRONG");
  }
  else {
    Serial.print(" CRC:OK");
  }
  // Start
  Serial.print(" S:");
  Serial.print(frame.Header1, HEX);
  Serial.print(" ");
  Serial.print(frame.Header2, HEX);

  // ID
  Serial.print(" ID:");
  Serial.print(frame.ID, HEX);

  // Voltage
  Serial.print(" V:");
  Serial.print(frame.Voltage);

  // Current
  Serial.print(" mA:");
  Serial.print(frame.Current);

  // Power
  Serial.print(" W:");
  Serial.print(frame.Power);

  // AccumulatedPower
  Serial.print(" kWh:");
  Serial.print(frame.AccumulatedPower);

  // Connected
  Serial.print(" Con.:");
  Serial.print(frame.ConsumersConnected);

  // Pairing
  Serial.print(" Pair:");
  Serial.print(frame.PairingFlag);

  // CRC
  Serial.print(" CRC:");
  Serial.print(frame.CRC);

  Serial.println();
  return frame.IsValid;
}

void EMT7110::AnalyzeFrame(byte *data, bool fOnlyIfValid) {
  struct Frame frame;
  DecodeFrame(data, &frame);
  DisplayFrame(data, frame, fOnlyIfValid);
}

bool EMT7110::CrcIsValid(byte data[]) {
  byte crc = 0;
  for (int i=0; i < FRAME_LENGTH; i++) {
    crc += data[i];
  }

  return crc == 0;
}


String EMT7110::GetFhemDataString(struct Frame *frame) {
  // Format
  //
  // OK  EMT7110  84 81  8  237 0  13  0  2   1  6  1  -> ID 5451   228,5V   13mA   2W   2,62kWh
  // OK  EMT7110  84 162 8  207 0  76  0  7   0  0  1
  // OK  EMT7110  ID ID  VV VV  AA AA  WW WW  KW KW Flags
  //     |        |  |   |  |   |  |   |  |   |  |
  //     |        |  |   |  |   |  |   |  |   |   `--- AccumulatedPower * 100 LSB
  //     |        |  |   |  |   |  |   |  |    `------ AccumulatedPower * 100 MSB
  //     |        |  |   |  |   |  |   |   `--- Power (W) LSB
  //     |        |  |   |  |   |  |    `------ Power (W) MSB
  //     |        |  |   |  |   |   `--- Current (mA) LSB
  //     |        |  |   |  |    `------ Current (mA) MSB
  //     |        |  |   |  `--- Voltage (V) * 10 LSB
  //     |        |  |    `----- Voltage (V) * 10 MSB
  //     |        |    `--- ID
  //     |         `------- ID
  //      `--- fix "EMT7110"

  // Header and ID
  String result;
  result += "OK EMT7110 ";
  result += (byte)(frame->ID >> 8);
  result += " ";
  result += (byte)(frame->ID);
  result += " ";

  // Voltage (V * 10)
  int volt = (int)(frame->Voltage * 10);
  result += (byte)(volt >> 8);
  result += " ";
  result += (byte)(volt);
  result += " ";

  // Current (mA)
  result += (byte)((int)frame->Current >> 8);
  result += " ";
  result += (byte)(frame->Current);
  result += " ";

  // Power (W)
  result += (byte)((int)frame->Power >> 8);
  result += " ";
  result += (byte)(frame->Power);
  result += " ";

  // AccumulatedPower (kWh * 100)
  int acp = (int)(frame->AccumulatedPower * 100);
  result += (byte)(acp >> 8);
  result += " ";
  result += (byte)(acp);
  result += " ";

  // Flags
  byte flags = 0;
  flags += frame->ConsumersConnected * 1;
  flags += frame->PairingFlag * 2;
  result += flags;


  return result;
}


bool EMT7110::TryHandleData(byte *data, bool fFhemDisplay) {
  if (data[0] == 0x25 && (data[1] == 0x6A || data[1] == 0x2A || data[1] == 0x40)) {
    struct Frame frame;
    DecodeFrame(data, &frame);
    if (frame.IsValid) {
	  if (fFhemDisplay) {
          String fhemString = "";
          fhemString = GetFhemDataString(&frame);
          if (fhemString.length() > 0) {
            Serial.println(fhemString);
          }
          return fhemString.length() > 0;
  	     }
  	     else {
		     return DisplayFrame(data, frame);
	     }
    }
  }
  return false;
}