LCD will not print when it is inside an if loop.

Other Hardware Displays
1

Hi. I have some code for a history project and my LCD works and it is wired up properly and the code uploads perfectly. But when I make the serial read my string it won't print on the LCD at all. It just stays blank. And the LCD will work when I just print something outside of this code.

#include<LiquidCrystal.h>
  LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
  String myQuestion;
  String msg=" Which Questoin do you want to ask me?";
   
  void setup() {
  lcd.begin(20,4);
  Serial.begin(9600);
 


  
}
  




void loop() {
  Serial.println(msg);
  while(Serial.available()==0) {
    
  }
  
   myQuestion=Serial.readString();
  
 if (myQuestion=="Q1") {
  lcd.clear();
  lcd.print("The constitution uses the words, God or creator.");


 }
 
 if (myQuestion=="Q1A")  {
  lcd.clear();
  lcd.print("TRUE");
 }
 
}
2

What is the line endings set to in serial monitor? If set to "Both NL & CR" the serial monitor will send
"Q1\r\n" which is not equal to "Q1". Change line endings to "No Line Endings" and try it.

no line ending.jpg
no line ending.jpg890×508 50.9 KB

no line ending.jpg
no line ending.jpg890×508 50.9 KB

3

Serial.println(msg);
while(Serial.available()==0)
{
????????
}

myQuestion=Serial.readString(); // shouldn't this be in the bracketed while request?

4

I solved it
i had this if (myQuestion=="Q1")
but I needed this if (myQuestion=="Q1\n")
adding the \n made it work

5

@canyonboy221

Other post/duplicate DELETED
Please do NOT cross post / duplicate as it wastes peoples time and efforts to have more than one post for a single topic.

Continued cross posting could result in a time out from the forum.

Hello.

Can take a few moments to Learn and Use The Forum

It will help you get the very best out of the forum in the future.

  • Your OS and version can be valuable information, please include it along with extra security you are using. Antivirus etc.

  • Always list the version of the IDE you are using and the board version if applicable.

  • Use quote or add error messages as an attachment NOT a picture.

  • How to insert an image into your post. ( Thanks @sterretje )

  • Add your sketch where applicable but please use CODE TAGS

  • Add a SCHEMATIC were needed even if it is hand drawn

  • Add working links to any specific hardware as needed (NOT links to similar items)

  • Remember that the people trying to help cannot see your problem so give as much information as you can

COMMON ISSUES

  • Ensure you have FULLY inserted the USB cables.

  • Check you have a COMMON GROUND where required. ( Thanks @Perry)

  • Where possible use USB 2.0 ports or a USB 2.0 POWERED HUB to rule out USB 3.0 issues.

  • Try other computers where possible.

  • Try other USB leads where possible.

  • You may not have the correct driver installed. CH340/341 or CP2102 or FT232 VCP Drivers - FTDI

  • There may be a problem with the board check or remove your wiring first.

  • Remove any items connected to pins 0 and 1.

COMPUTER RELATED

  • Close any other serial programs before opening the IDE.

  • Ensure you turn off any additional security / antivirus just to test.

  • There may be a problem with the PC try RESTARTING it.

  • You may be selecting the wrong COM port.

  • Avoid cloud/network based installations where possible OR ensure your Network/Cloud software is RUNNING.

  • Clear your browsers CACHE.

  • Close the IDE before using any other serial programs.

  • Preferably install IDE’s as ADMINISTRATOR or your OS equivalent

ARDUINO SPECIFIC BOARDS

  • CH340/341 based clones do not report useful information to the “get board info” button.

  • NANO (Old Types) some require you to use the OLD BOOTLOADER option.

  • NANO (ALL Types) See the specific sections lower in the forum.

  • NANO (NEW Types) Install your board CORE’s.

  • Unless using EXTERNAL PROGRAMMERS please leave the IDE selection at default “AVRISP mkII”.

  • Boards using a MICRO usb connector need a cable that is both DATA and CHARGE. Many are CHARGE ONLY.

CREATE editor install locations.

  • On macOs ~/Applications/ArduinoCreateAgent-1.1/ArduinoCreateAgent.app/Contents/MacOS/config.ini

  • On Linux ~/ArduinoCreateAgent-1.1/config.ini

  • On Windows C:\Users[your user]\AppData\Roaming\ArduinoCreateAgent-1.1

Performing the above actions may help resolve your problem without further help.

Language problem ?

Try a language closer to your native language:

Thanks to all those who helped and added to this list.

6

This topic was automatically closed after 76 days. New replies are no longer allowed.