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  1. Home
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  3. A more convenient Arduino Uno

A more convenient Arduino Uno

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  • N Offline
    N Offline
    NeverDie
    Hero Member
    wrote on last edited by NeverDie
    #1

    I ran across this Keyestudio Arduino Uno which has a convenient feature: you can easily switch it from 5v mode to 3.3v mode. When working with radios, most of which take 3.3v, it turns out that's a very nice convenience. Just saying.

    https://www.amazon.com/KEYESTUDIO-Arduino-ATmega328P-Controller-Development/dp/B085RHTBJT?ref_=ast_sto_dp

    The price is what it is, but it's the same price in the Keyestudio store on aliexpress.

    If anyone knows of a cheaper, equivalent board, that runs at 3.3v (with or without a switch) please post. I tend to use 3.3v pro mini's, but I don't believe they can handle quite as much power, and obviously the form factor is different. Connecting to a pro mini with either an FTDI or CP2102 is yet another hassle.

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    • N Offline
      N Offline
      NeverDie
      Hero Member
      wrote on last edited by NeverDie
      #2

      Well, scratch all that. It apparently can supply only 50ma at 3.3v. Disappointing!

      I suppose the way to do it would be to find a 3.3v LDO with decent current capability and the same footprint as the standard 5v LDO (and good heat dissipation!), and then do a swap on a generic board by desoldering the 5v LDO and soldering in the 3.3v LDO. And it would be cheaper as well.

      Also, I do wonder if it handled switching from 16Mhz to 8Mhz when switching from 5v to 3.3v? Or does it run at 8Mhz regardless?

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      • E Offline
        E Offline
        ejlane
        wrote on last edited by
        #3

        It says that it has a 16MHz oscillator, so it's most likely running at 16MHz either way. Definitely not in spec, but with a cheap clone like this, not surprising. Most people who buy it wouldn't be able to track down a weird bug that happens once in a while back to it running out of spec. Likely it will work okay on a bench, but I wouldn't put anything critical on it.

        I wonder if it's a real Atmega328 on it, or some clone? No telling these days what you're gonna get.

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        • Michiel van der WulpM Offline
          Michiel van der WulpM Offline
          Michiel van der Wulp
          wrote on last edited by
          #4

          I also have a few of such Arduino Unos with a 3.3V selection switch from the shop "Open Smart" on Aliexpress.
          See picture at: https://michiel.vanderwulp.be/domotica/Modules/ArduinoUno/#open-smart-3-3v-5v-switchable-uno-specification-1
          They work fine, also on 3.3V.

          But indeed, running it at 16MHz on 3.3V is out of spec...

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          • Michiel van der WulpM Offline
            Michiel van der WulpM Offline
            Michiel van der Wulp
            wrote on last edited by
            #5

            I even managed to solder a nRF24L01+ to the board so everything works on 3.3Volt, and this node works fine.
            This took a lot of scratching copper from the board...

            uno3vnrfs.jpg

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