I made a working model of Bluetooth light control with arduino and Bluetooth. Everything worked fine and then after some time I connected the circuit again it didn't work and the pins 7,10,11,12 aren't working . I was using a Bluetooth shield but I tried the simple LED flash program and even that's not working .

Please suggest any good way of making it working again or at least explain what happened with it.

  • 1
    If a blink sketch on those pins no longer works, it’s likely that they are destroyed. Mar 13, 2014 at 18:19
  • Do sketches download to the board OK or do you get an error message? If they download OK, does blink work on other pins? If so, which ones does it work on/which ones does it not work on?
    – sachleen
    Mar 16, 2014 at 0:21
  • Which bluetooth shield were you using?
    – asheeshr
    Mar 16, 2014 at 1:36

1 Answer 1


Try running the blink LED, on a different terminals. If the LED is working properly, then most likely the pins are destroyed. Why are they destroyed? Most likely, you've withdrawn more current than the pins can actually provide.

According to the datasheet of the Arduino uno, the IO pins can handle up to 40mA.

enter image description here

The only possible way to solve this problem is to change the IC (Atmega328) by another one. It's not guranteed that it will work, but the microcontroller is reletively cheap.

The definite answer can not be determined unless you showed us a schematic of your connection.

  • Note that a plain ATmega328 will not have a bootloader and would need ISP programming. Mar 16, 2014 at 10:33
  • But it's also easy to find ATmega328 with Arduino UNO bootloader flashed in already; then the unit price may increase a little bit though (~$1)
    – jfpoilpret
    Mar 16, 2014 at 11:08

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