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.

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    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?

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  • 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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