Introduction: Arduino Nano CH340 Chinese Build Optiboot HACK ! Part 2 - 3.3v 8 Mhz Version for Low Power Applications !!

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Okay so it wasnt Enough for me Tweaking this PCB to Run The Optiboot Space Saving Bootloader...

i came across another problem..

I have quite a lot of these Awesome Nokia 5110 LCD Display's hanging around and they are 3.3v ONLY.

Some are 5v tolerant but my ones are NOT..

Yes - i could of used a Voltage Divider but that woulda meant extra parts that i dont have..

I do have 8 Mhz crystals though..

Plus, if i wanted to run this Arduino Nano on battery power - i would have a low-power version that will last longer than a 5v version :)

i also tried 10k resistors on the data lines for the Nokia 5110 LCD displays, still didnt work no matter what i did lol

So after deliberation, i thought of hacking the Nano, again lol

So Step 1 is to First Desolder the SMD Crystal, which by the way, is such a SEXY size haha - its TINY !!!! Actually, its not a Crystal - its a RESONATOR which is much less PRECISE than a crystal so by doing this mod, one is improving the functionality of this little Arduino PCB !

here's a close-up

Step 1: De-Soldering the Components for Replacement

And So begins my next adventure to get this Chinese-Made Arduino Nano Compatible to a 3.3v Low Power version with bootloader that only takes up 1.5K of space out of the 32K worth of programming space available on the ATMEGA328P-AU Microcontroller :))

So that's 30.5K worth of Code-Space that this project will Yield, as with a 3.3v Arduino-Nano Compatible !

The SMD resistor is pretty darn easy to de-solder, using my regular soldering iron tip which ive never changed since buying it almost 8 years ago, not a fancy soldering iron either, just a £15/$20 version from ebay..

Just applying heat on either side of it very quickly and using a pair of precision tweezers, ALOT of light, and i mean, ALOTTTTTTTTTTTT of LIGHT !!!

During the daytime, using blinding LED light sources, lol Okay so it might be overkill, but its very important to have alot of light (NOT warm-white light, if you can help it) to solder, as these SMD components are really tiny, 3.2mm x 1.3 mm !!!! !!!! !!! !! !

OMG THATS TINY !!! lol

So um, yup, real-small lol

Very carefully and not applying too much heat at any one time, so i can re-use it for another PCB i will no doubt make in the future lol

Okay so heres after its been removed, Now, as you can see from the picture, the ATMEGA328P-AU's traces goes to the pads of the Crystal, so we now know where to solder the crystal. Also there is a 5v AMS1117 voltage regulator on the underside of the PCB that i need to de-solder and replace with a 3.3v one, which i also have the same manufacturer's 3.3v version as i made PCB's for both 5v and 3.3v once upon a time.

So the De-Soldering and soldering of parts was a mini project in itself, Step 2 for the Optiboot Bootloader HACK lol !

Step 2: Step 2 - the 3.3v Optiboot Bootloader Hack !

Same as my method in my other instructable of how i got the 5v Optiboot Bootloader onto this PCB, but if youve not seen it, i'll quickly go over it again here;

Basically, we need to FOOL the Bootloader Program that it has the correct pins allocated to its input/outputs, so using the 2 pictures HERE and HERE we need to 'DECIPHER' the SMD Atmega328P to the Through-Hole version's pins, which there are just 4 pins to connect up, with the addittion of the two power connections too, which makes 6 pins in total..

Once wired up, like THIS, Run the Optiboot Bootloader Sketch and itll automatically Load the New 3.3v 8Mhz Bootloader to the Arduino Nano-Compatible !!

There ya go, nice and simple, quick and possibly my shortest instructable ever lolz

Any questions, fire away, remember the "Be Nice" policy, constructive criticism of course welcomed, but anything negative, please keep it to yourselves :P recovering from depression, so it'd be awesome for no negativity & wholeheartedly appreciated :)