Hello Joe,

I would like to tell you that the setup() function is used to execute the initialization commands like to start the hardware like pins and LCD in this case. Your lcd.begin(16,2) should come in the setup() function. Also, the commands which are supposed to be executed infinitely until the power is switched off from Arduino, we use loop(). Here, lcd.print("hello, world!") command should be in the loop() function.

Now, the flickering of LCD can be because of one most common reason, that is, updates. When Arduino frequently updates the characters, it looks like if the LCD is flickering but actually the LCD is printing the same thing again and again. I would recommend you to remove any lcd.clear() command when not required to use. Also, try updating the characters only the one which is supposed to be updated rather than clearing and reprinting the whole data.
You can go here for more: https://www.eevblog.com/forum/beginners/arduino-lcd-code-problem-lcd-flickering/

Do feel free to ask more and please read and respect more projects on my profile.

~Techmirtz

Thanks for A2A!

Well, it quiet difficult to use UNO as it as lesser memory. It can create problem in processing and execution even if you fill the memory of UNO up to the brink by reducing the code size. It suggest you to use MEGA2560 rather!

Hi,
Thanks for working on my project.
Please check that all the libraries have been successfully installed.