After struggling with an LCD showing rubbish characters on my previous post, I found that my pin 5 was dead, for no reason. I never connected it to anything except the LCD - I bought it two days ago.

I'm glad that I bought two extra ATmega328P-PU along with it, burned bootloader into it, and it worked, but what causes my pin 5 to be dead?

I did use A5 as an input before, but I don't get how it affected PWM pin 5.

FYI, this is my first time playing with Arduino.

closed as unclear what you're asking by Chris Stratton, Majenko, dlu, Madivad, Mikael Patel Feb 13 '16 at 10:13

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  • 2
    Sorry you are having difficulties, but this is not even remotely answerable as a question without the full details of your exact setup and procedures. It's wintertime in the northern hemisphere, perhaps your workspace is static prone? – Chris Stratton Jan 28 '16 at 5:54

I have quite a few Arduinos lying around and only one has failed completely, which I think is because I "zapped" it with static electricity, which is a problem, as Chris Stratton suggested.

Make a habit of grounding yourself before handling electronics, for example by touching some metal (earthed) part before reaching for your Arduino. Don't work while standing on a synthetic carpet, for example.

but what causes my pin 5 to be dead?

Possible reasons:

  • static electricity
  • accidentally shorted an output pin to ground, which could damage the output driver if you are outputting HIGH
  • accidentally connected an output pin to +5V, which could damage the output driver if you are outputting LOW
  • connected the pin to a negative voltage
  • connected the pin to more than +5V
  • powering the board "parasitically" which means connecting power to the data pins before connecting power to the main power input
  • tried to "sink or source" more than 40 mA which is the absolute maximum rating. For example, connecting an LED directly to the pin without a current-limiting resistor

The other link he refers to: Bad LCD? Bad microcontroller? Or what?

  • Forreset Gump would also say, "It happens". Someone fingered some ICs, decades ago, asking me, "Are these those new CMOS type chips?" to which I replied, "They were". – Rob Jan 28 '16 at 14:16

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