ZPA_elektromer_UARTtest/ZPA_elektromer_UARTtest.ino

#include <WiFi.h>
#include <WiFiClient.h>
#include <ArduinoOTA.h>

const char* host = "zpaesp32";
const char* ssid = "...";
const char* password = "...";

void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  Serial.println("Booting...");
  WiFi.mode(WIFI_STA);

  Serial.print("Wifi connect... ");
  WiFi.begin(ssid, password);
  while (WiFi.waitForConnectResult() != WL_CONNECTED) {
    Serial.println("Connection Failed! Rebooting...");
    delay(5000);
    ESP.restart();
  }
  Serial.println("Connected");

  Serial.print("Configure OTA... ");
  ArduinoOTA
  .onStart([]() {
    String type;
    if (ArduinoOTA.getCommand() == U_FLASH)
      type = "sketch";
    else // U_SPIFFS
      type = "filesystem";

    // NOTE: if updating SPIFFS this would be the place to unmount SPIFFS using SPIFFS.end()
    Serial.println("Start updating " + type);
  })
  .onEnd([]() {
    Serial.println("\nEnd");
    Serial.println("Disconnect from wifi");
    WiFi.disconnect();
  })
  .onProgress([](unsigned int progress, unsigned int total) {
    Serial.printf("Progress: %u%%\r", (progress / (total / 100)));
  })
  .onError([](ota_error_t error) {
    Serial.printf("Error[%u]: ", error);
    if (error == OTA_AUTH_ERROR) Serial.println("Auth Failed");
    else if (error == OTA_BEGIN_ERROR) Serial.println("Begin Failed");
    else if (error == OTA_CONNECT_ERROR) Serial.println("Connect Failed");
    else if (error == OTA_RECEIVE_ERROR) Serial.println("Receive Failed");
    else if (error == OTA_END_ERROR) Serial.println("End Failed");
  });

  Serial.println("OK");

  Serial.print("Starting OTA... ");
  ArduinoOTA.begin();
  Serial.println("OK");

  Serial.print("Configure Reading serial port... ");
  Serial2.begin(300, SERIAL_7E1, 36, 4);
  Serial.println("OK");

  Serial.println("Test ZPA elektro");
  Serial.println("================");
  Serial.println();
  Serial.println("R - Request (sends /?!<CR><LF>)");
  Serial.println("C - Change baudrate to 4800 (sends <ACK>040<CR><LF>)");
  Serial.println();
  Serial.println("Manual baudrate");
  Serial.println("1 - 300b");
  Serial.println("2 - 1200b");
  Serial.println("3 - 2400b");
  Serial.println("4 - 4800b");
  Serial.println("5 - 9600b");
  Serial.println();
  Serial.println();
  Serial.println("Ready");
  Serial.print("IP address: ");
  Serial.println(WiFi.localIP());

}

// BCC is calculated as follows (source https://github.com/lvzon/dsmr-p1-parser/blob/master/doc/IEC-62056-21-notes.md):
// The BCC is calculated over the bytes after STX up to and including the ETX byte
// To calculate this BCC, take the first byte XOR 0xff
// XOR this value with the second byte, and so forth up to and including the last byte (include 0x03 ETX !!),
// and XOR the final value with 0xff.

uint8_t localBCC;

void loop() {

  ArduinoOTA.handle();


  if (Serial2.available()) {
    char r = Serial2.read();

    if (r == 0x02) {
      Serial.print("<STX>");
      localBCC = 0xFF; // Set checksum to 0xFF (first byte is XORed with 0xFF)
      return;
    }

    if (r == 0x03) {
      Serial.println("<ETX>");
      Serial.print("Checksum <BCC>: ");
      Serial.print(Serial2.read());
      Serial.println();
      Serial.print("Calculated <BCC>: ");
      localBCC = localBCC ^ r;    // Include last byte (ETX) to checksum
      localBCC = localBCC ^ 0xFF; // Final value XORed with 0xFF
      Serial.print(localBCC);
      Serial.println();
      Serial.println();
      Serial.println("Changing back baudrate to 300");
      Serial2.updateBaudRate(300);
      return;
    }

    // Calculate BCC checksum
    localBCC = localBCC ^ r;
    Serial.write(r);
  }


  if (Serial.available()) {
    char r = Serial.read();

    if (r == 'R') {
      Serial.println("Requesting data");
      Serial2.print("/?!\r\n");
      return;
    }

    if (r == '1') {
      Serial.println("Baudrate to 300");
      Serial2.updateBaudRate(300);
    }

    if (r == '2') {
      Serial.println("Baudrate to 1200");
      Serial2.updateBaudRate(1200);
    }

    if (r == '3') {
      Serial.println("Baudrate to 2400");
      Serial2.updateBaudRate(2400);
    }

    if (r == '4') {
      Serial.println("Baudrate to 4800");
      Serial2.updateBaudRate(4800);
    }

    if (r == '5') {
      Serial.println("Baudrate to 9600");
      Serial2.updateBaudRate(9600);
    }

    if (r == 'C') {
      Serial.println("Change baudrate");
      Serial2.write(0x06);
      Serial2.print("040\r\n");
      Serial2.flush();
      Serial2.updateBaudRate(4800);
      return;
    }

    Serial2.write(r);
  }

}