Multi-functional Power Box

I am excited to unveil a newly developed multi-functional power box, designed speficially for engineering-related projects.
This versatile device is equipped with several key features to streamline your work.

Key Features

• Dual Relay System:

  • Outlet 1: Connected to a solid-state relay, perfect for use in PID control systems.
  • Outlet 2: Equipped with a mechanical relay, ideal for simple on/off power operations.

• Integrated AC Power Meter:

  • Provides instant and accurate measurements of current and voltage, with a precision of ±1 W.

• Expandable with Arduino Mega:

  • The embedded Arduino Mega board allows for easy expansion. You can add modules for monitoring temperature, pressure, and more, making this power box highly adaptable for future developments.

For a closer look, check out the images of the power box below:

Arduino Code

The board comes pre-loaded with essential Arduino code, ensuring the power box is ready to use straight out of the box.

/*
  Title: Dual Relay Controller
  Made by: YX
  Location: Melbourne
  Date: 20241010
  Description: This program is designed to control two relays, one mechanical and one SSR (Solid State Relay),
  allowing for triggering via serial commands.
  Expansion: The function can be extended to measure AC power, voltage, current when using PZEM004T.
*/
#include <PWM.h>  //download https://code.google.com/archive/p/arduino-pwm-frequency-library/downloads
// edit ATimerDefs.h and add '(0,0,0,0,0), // TIMER1C'  after Line 107
// if applied to Arduino Mega 2560
#include <PZEM004Tv30.h>  // Power meter library
#include <math.h>
/*
  This code runs on mega and uno.
*/
PZEM004Tv30 pzemOT1(68, 69);  // power meter

float power1;
float voltage1;
float current1;
float factor1;

float powerx;
int relayPin = 28;

// initializ the SSRs
//use pin 11 on the Mega instead, otherwise there is a frequency cap at 31 Hz
//  ledTimer0  Pins 13, 4  might influence the internal clock
int ledTimer1 = 5;      // Pins 11, 12 16-bits timer
int32_t frequency = 1;  //PWM frequency (in Hz)

int mark = 0;
// String comdata = "";       // initialize input string
int numdata[2] = { 0 };
float DutyCircle;
const byte numChars = 32;
char comdata[numChars];

boolean newData = false;

void setup() {
  //initialize all timers except for 0, to save time keeping functions
  InitTimersSafe();
    pinMode(relayPin, OUTPUT);  
  digitalWrite(relayPin, LOW);
  //sets the frequency for the specified pin
  bool success1 = SetPinFrequencySafe(ledTimer1, frequency);
  Serial.begin(115200);  // set up communication
  digitalWrite(ledTimer1, LOW);
  Serial.println("Power box");

}

void loop() {
  int j = 0;
  while (!Serial) {
    ;  // wait for serial port to connect. Needed for native USB
  }
  recvWithStartEndMarkers();
  if (newData == true) {
    if (comdata[0] == 'P' && comdata[1] == 'W') {
      Serial.println("power reading");
      powerx = pzemOT1.power();
      //    voltage1 = pzemOT1.voltage();
      //    current1 = pzemOT1.current();
      //    power1 = voltage1 * current1;
      power1 = pzemOT1.power();
      //    factor1 = pzemOT1.powerfactor();
      if (!isnan(power1)) {
        //        Serial.print("1: ");
        Serial.print(power1);
        Serial.println();
      } else {

        Serial.println("1: OFF");
        // Serial.print(voltage1); Serial.println();
        // Serial.print(current1); Serial.println();
      }
      mark = 0;
    }

    if (comdata[0] == 'S' && comdata[1] == 'O' && comdata[2] == '1') {
      delay(2);
      mark = 1;
      char* commaPtr = strchr(comdata,',');
      // Check if the comma exists
     if (commaPtr != NULL) {
      float value = atof(commaPtr + 1); // Convert string after the comma
            // Now you can use 'value' as a float
      if (value < 256){      
      pwmWrite(ledTimer1, value);  // change the duty circle
      float DutyCycle = float(value) / 255 * 100;
      Serial.print("SSR Relay Activate and The Duty Cycle is ");
      Serial.println(DutyCycle);
      } else {
        Serial.println("Exceeds 255; ignoring.");
      }
     } else {
      Serial.println("SSR Relay Deactivate");
     }
         }

    if (comdata[0] == 'S' && comdata[1] == 'O' && comdata[2] == '2') {
      delay(2);
      Serial.println("Relay On");
      delay(10);
      digitalWrite(relayPin, HIGH);
      mark = 0;
    }

    if (comdata[0] == 'S' && comdata[1] == 'F' && comdata[2] == '2') {
      delay(2);
      Serial.println("Relay Off");
      delay(10);
      digitalWrite(relayPin, LOW);
      mark = 0;
    }
    newData = false;
  }
}



void recvWithStartEndMarkers() {
  static boolean recvInProgress = false;
  static byte ndx = 0;
  char startMarker = '<';
  char endMarker = '>';
  char rc;

  // if (Serial.available() > 0) {
  while (Serial.available() > 0 && newData == false) {
    rc = Serial.read();
    delay(2);

    if (recvInProgress == true) {
      if (rc != endMarker) {
        comdata[ndx] = rc;
        ndx++;
        if (ndx >= numChars) {
          ndx = numChars - 1;
        }
      } else {
        comdata[ndx] = '\0';  // terminate the string
        recvInProgress = false;
        ndx = 0;
        newData = true;
      }
    }

    else if (rc == startMarker) {
      recvInProgress = true;
    }
  }
  mark = 1;
}

I also attach a demo MATLAB code in the following.

function s = serialRelayControl(action, varargin)
    % serialRelayControl Handle serial port actions 
    % Created by YX on 2024.10.12
    %
    % Copyright (c) 2024 YX
    % All rights reserved.
    % Commerical use is prohibited without explicit permission
    % Examples:
    % Create: s = serialRelayControl('create', 'COM7');
    % Write: serialRelayControl('write', s, 'yourCommand');
    % Remove: s = serialRelayControl('remove', s);
    
    action = lower(action);  
    switch action
        case 'create'
            port = varargin{1};
            s = createPort(port);
            readFromPort(s);        
        case 'write'
            s = varargin{1};
            command = varargin{2};
            writeToPort(s, command);
            readFromPort(s);
        case 'remove'
            s = varargin{1};
            removePort(s);
        otherwise
            error('Unknown action.');
    end
end

function s = createPort(port)
    try
        s = serialport(port, 115200);
        s.Timeout = 5;
    catch ME
        warning('Failed to create serial port: %s', ME.message);
        s = [];
    end
end

function writeToPort(s, command)
    if ~isempty(s) && isvalid(s)
        try
            pause(.1);
            writeline(s, command);
            pause(.1);
        catch ME
            warning('Failed to write to serial port: %s', ME.message);
        end
    else
        disp('No active serial port connection.');
    end
end

function readFromPort(s)
    if ~isempty(s) && isvalid(s)
        try
            pause(.1);
            if s.NumBytesAvailable > 0
                output = readline(s);
               pause(.1);
                disp(['Received: ', output]);
            else
                disp('No data available.');
            end
        catch
            warning('Error reading from serial port.');
        end
    else
        disp('No active serial port connection.');
    end
end

function removePort(s)
    if ~isempty(s) && isvalid(s)
        delete(s);
        disp('Serial port connection removed.');
    else
        disp('No active serial port connection to remove.');
    end
end

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