Arduino serial communication to display on LCDWG128x64

[raffy0991]

Hi Guys,

Need your help This is part of my project where I need to read serial communication from a device/pc and display it in LED array 5 digit 7 segment. However, as of now I would like to read the value given by a PC and display it to an LCD for testing purposes.

I am using COM PORT 3 of my PC then usb to mini usb cable to arduino. Then I connected my arduino to a WG12864 (LCD 128x64 device). My connections are all good it is just I have a problem with my program. For example I wanted to display "1" from PC to LCD it will display "1" (using serial monitor in Arduino IDE). When I type "2" it will display "12". Basically, it does delete the previous data. I wanted to delete the previous data after I pressed enter. See pictures below. This is using "No Line ending. When I use "New Line", it does not display anything.

The code is below, I just copied this codes from other examples and I experimented it. I think the problem is when I received \r or \n it does not refresh the display or data. I hope you could help me with this.

#include "U8glib.h"

U8GLIB_ST7920_128X64_4X u8g(13, 11, 12);

String inputString = "";
boolean stringComplete = false;
String command = "";
String value = "";
char inChar = "";
void draw(void) {

  u8g.setFont(u8g_font_unifont);
 u8g.setPrintPos(1,20);
 u8g.print(inputString);
  //u8g.setFont(u8g_font_osb21);
  //u8g.drawStr( 0, 22, "Hello World");
}

void setup(void) {


  // assign default color value
  Serial.begin(9600);
  inputString.reserve(50);  // reserve 50 bytes in memory to save for string manipulation 
  if ( u8g.getMode() == U8G_MODE_R3G3B2 ) {
    u8g.setColorIndex(255);     // white
  }
  else if ( u8g.getMode() == U8G_MODE_GRAY2BIT ) {
    u8g.setColorIndex(3);         // max intensity
  }
  else if ( u8g.getMode() == U8G_MODE_BW ) {
    u8g.setColorIndex(1);         // pixel on
  }
  else if ( u8g.getMode() == U8G_MODE_HICOLOR ) {
    u8g.setHiColorByRGB(255,255,255);
  }
  

}

void loop(void) {
  // picture loop
  while (Serial.available()>0) {
    // get the new byte:
    char inChar = (char)Serial.read();
    inputString += inChar;
    // add it to the inputString:
    // if the incoming character is a newline or a carriage return, set a flag
    // so the main loop can do something about it:
    if (inChar == '\n' || inChar == '\r') {
      stringComplete = true;
    } 
  }
  if (stringComplete) {
    //Serial.println(inputString);
    delay(100);
    // identified the posiion of '=' in string and set its index to pos variable
    int pos = inputString.indexOf('=');
    // value of pos variable > or = 0 means '=' present in received string.
    if (pos > -1) {
      // substring(start, stop) function cut a specific portion of string from start to stop
      // here command will be the portion of received string till '='
      // let received string is open=test123
      // then command is 'open' 
        command = inputString.substring(0, pos);
      // value will be from after = to newline command
      // for the above example value is test123
      // we just ignoreing the '=' taking first parameter of substring as 'pos+1'
      // we are using '=' as a separator between command and vale
      // without '=' any other character can be used
      // we are using = menas our command or password must not contains any '=', otherwise it will cause error 
        value = inputString.substring(pos+1, inputString.length()-1);  // extract command up to \n exluded
       //Serial.println(command);
       //Serial.println(value);
       // password.compareTo(value) compare between password and value string,if match return 0 


  
        } 
       // clear the string for next iteration
       inputString = "";
       stringComplete = false;
    }  

    
  u8g.firstPage();  
  do {
    draw();
  } while( u8g.nextPage() );
  
  // rebuild the picture after some delay
  //delay(50);
}

[sterretje]

@raffy0991

Basically, it does delete the previous data.

You mean "doesn't"

You will need to clear the screen when you have a new valid message. Or at least position the cursor and overwrite the existing text. I'm not familiar with your screen so can't advise further.

[b707]

What do you enter in serial Monitor to send '1' or '2' ?
In the code I see that you must enter something like "=2" in the monitor?

[raffy0991]

Yeah, I just realized the code needs '=' to refresh or delete the data. My problem now is that I do not know the set of data that the device is sending. I tried reading it through Putty and Accessport but I do not understand anything because it is all hex codes and when I tried to convert it to char it does not make sense. I will attach the data here tomorrow maybe.

Anyway, is possible if I reduce this "inputString.reserve(50); // reserve 50 bytes in memory to save for string manipulation" to inputString.reserve(5); it will delete the previous data where there is more than 5 bytes?

[raffy0991]

You will need to clear the screen when you have a new valid message. Or at least position the cursor and overwrite the existing text. I'm not familiar with your screen so can't advise further.

I use an LCD 128x64 screen. How can I overwrite this existing text? Do you have a code I can follow?

[raffy0991]

Hi Guys,

Already solved my problem. My code is below. My problem now is how to connect it to my device I have a GSE460 a digital weight indicator it has rs232 db9 female connector and I have a rs232 TTL Db9 female connector too. Is the connection as simple as connecting the RX, TX and GND of the device to the rs232 ttl as shown below?

#include <U8glib.h>    // Include the U8glib library

#include <SoftwareSerial.h>

SoftwareSerial mySerial(A0, A1); // RX | TX

U8GLIB_ST7920_128X64_4X u8g(13, 11, 12);  // Initialize the LCD object

String receivedData = "";   // String to store the received data
long numberValue = 0;       // Variable to store the extracted number as a long

void setup() {
  mySerial.begin(9600);       // Initialize Serial communication
}

void loop() {
  if (mySerial.available()) {
    char receivedChar = mySerial.read();    // Read a character from the Serial port

    // Check if the received character is a valid numerical value ('0'-'9') or a space
    if ((receivedChar >= '0' && receivedChar <= '9') || receivedChar == ' ') {
      // Skip leading spaces
      if (receivedData.length() > 0 || receivedChar != ' ') {
        receivedData += receivedChar;   // Add the character to the received data String
      }
    }
    // If the received character is a newline '\n', then convert the received data String
    // to a long integer and display it on the LCD
    else if (receivedChar == '\n' && receivedData.length() > 0) {
      numberValue = extractNumberFromData(receivedData); // Convert String to long integer
      lcdDisplayNumber(numberValue);      // Display the extracted number on the LCD
      receivedData = "";                 // Clear the receivedData String for the next number
    }
  }
}

// Function to extract the number from the String and convert it to a long integer
long extractNumberFromData(String data) {
  long extractedNumber = 0;
  bool isNegative = false;
  int startIndex = 0;

  // Check if the first character is a minus sign '-'
  if (data.charAt(0) == '-') {
    isNegative = true;
    startIndex = 1; // Start extracting the number from the second character
  }

  // Convert the numeric characters into a long integer
  for (int i = startIndex; i < data.length(); i++) {
    if (data.charAt(i) >= '0' && data.charAt(i) <= '9') {
      extractedNumber = extractedNumber * 10 + (data.charAt(i) - '0');
    }
  }

  // Apply the negative sign if applicable
  if (isNegative) {
    extractedNumber *= -1;
  }

  return extractedNumber;
}

// Function to display the number on the LCD
void lcdDisplayNumber(long number) {
  u8g.firstPage();
  do {
    u8g.setFont(u8g_font_8x13B);
    u8g.drawStr(0, 20, "Extracted Num:");
    u8g.setFont(u8g_font_fur11);
    u8g.setPrintPos(0, 40);  // Set the position to print the extracted number
    u8g.print(number);       // Display the extracted number
  } while (u8g.nextPage());
}