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I have this small project with PIC microcontroller and LCD display WH1602A-TTI-ET. I am controlling the backlight via software, so I attached it to +5V via PNP transistor that is controlled by one of the pins of the PIC microcontroller.

The problem I have is that when I am flashing new program into the microcontroller it seems to randomly send out some "noise" on its pins (which is probably normal) and the LCD backlight keeps going on and off incredibly fast and I am worried this might damage it.

Since I am no expert in LED electronics my simple question is - can this wear it out or damage it? Should I physically disconnect it in times when I am flashing new program, or it doesn't matter?

Petr
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  • That backlight is simply a single LED. That won't get damaged with some blinks. – Tirdad Sadri Nejad Jun 09 '22 at 20:08
  • Could you please post a link to a datasheet? The one available here (https://www.winstar.com.tw/products/character-lcd-display-module/lcd-display-16x2.html) doesn't help much. – devnull Jun 09 '22 at 20:13
  • Sorry I don't have any better datasheet. It's sometimes high frequency blinking (like ~20 per second). But I guess if LED can withstand that easily, then it doesn't matter. I am sure incandescent light would be dead quickly under this stress. Thanks – Petr Jun 09 '22 at 20:28
  • You're not wrong... If it weren't an LED, you could have an issue. You'll need to get it well over 60Hz if you don't wanna see visible flicker. Note that the EU is clamping down on flashing lights... They consider anything in the 4-60Hz to be epileptic seizure territory. – Kyle B Jun 09 '22 at 21:21

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It's quite common to use PWM (on/off switching) control of the LED backlights of displays so there shouldn't be any problem if you have some occasional flicker during programming. But it's good practice to keep this in mind when doing circuits which are sensitive to this. Usually this is solved with some kind of buffering that inhibits the signals to propagate during programming.

Dejvid_no1
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