LCD display "timer started" in my LCD display but after 5 minutes the LCD display came out with a lot of junk symbols and character
May I know why?

 

Could be noise.
Put a 10μF 10V electrolytic capacitor across Vcc and GND at the LCD.

 

LCD display "timer started" in my LCD display but after 5 minutes the LCD display came out with a lot of junk symbols and character
May I know why?

Because your code is overwriting the original pixels without clearing the pixels first.

 

Because your code is overwriting the original pixels without clearing the pixels first.

Mean that every time I need to clear my screen?

 

Are you accessing it via the parallel connection or SPI or I2C?

 

Because your code is overwriting the original pixels without clearing the pixels first.

Not on a character mode display like that one.

 

guys how to solve this problem?

 

Hi Alex,
Post your program Code.
E

 

guys how to solve this problem?

Are you accessing it via the parallel connection or SPI or I2C?
until we know this, how do you expect us to debug it for you?

 

You have omitted a lot of important information.

What MCU are you running?
Where is the circuit diagram?
Where is the program listing?
How long are the wires between the MCU and LCD?

 

You left out a lot of information that we need to give you an accurate diagnosis.
From what you posted, it appears that the coding is correct because it runs OK for the first few minutes. Those displays take quite a lot of current. How are you powering it? If you are powering it from an Arduino 5V output, you are probably overheating the regulator chip and causing the supply to be marginal. I recommend that you use a separate 5V supply for the display.

 

I have experience running an LCD on an Arduino and have had this problem - but don’t know if you have an Arduino or what LCD you are using or how you are connecting to it (SPI or I2C) or what library you are using or if there’s a problem in your code.

 

Can you try a different LCD, just in case it's defective?