I have a HC-05 module which works absolutely fine with an Arduino Uno. Because I need to reduce the size of it, I tried using an Arduino Nano.

After correctly wiring it up to the Nano, sometimes the LED doesn`t turn on, or sometimes it does not appear in the devices listing of my smartphone. It also resets randomly the Arduino. I have tested it and it fully works without any problems with the Uno.

I think it is a power issue, but not from my computer or any other computer because I tried on all my computers.

  • Are you powering it from 3.3V or 5V? – Majenko Aug 23 '18 at 13:35
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    the regulator on the nano may not be able to supply enough current for the HC-05. See if you can find a part number on the regulator and look up its specs. – Chad G Aug 23 '18 at 15:35
  • @ChadG If it's running from the 3.3v pin then it may even be using the internal 3.3v regulator of the CH340G, in which case you'd be lucky to get a few tens of mA from it... – Majenko Aug 23 '18 at 16:28
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    Please provide a schematic and the type of HC-05 module you have. The HC-05 itself runs in 3.3V, but most modules, that you can buy, add an extra voltage regulator for 5V, so that you can power it directly from the Arduino. – chrisl Aug 23 '18 at 21:39

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