Powering a 5V Pro Micro (The Hard Way)

Hi. I have a Pro Micro (5V) and with the 5 volts needed, there comes a lot of problems. I think a possible answer would be to modify the board and remove the 5 volt regulator, like what @Cheungbx did with his Ardubaby (great creation by the way!) but I don’t have enough guts to modify and possibly destroy my 30$ Arduino. I did buy a 3.7v lipo charger (the Adafruit Micro Lipo) but it doesn’t boost the voltage. Instead, I thought I would save some money by just buying a boost module. Paired with the charger. I has no idea how I would connect the two unfortunately, I’m not an expert at this kind of stuff. Here’s the booster and here’s the charger:

Thanks for the help! :smiley:

Alternatively, I am thinking about buying this charger/booster

There’s no need to remove the on-board regulator. It can be bypassed by using the VCC pin as a power input instead of the RAW pin.

Like the Arduboy, a Pro Micro will almost certainly run without problems at the 3V to 4.2V that a LiPo battery would provide.

You could use your Adafruit charger to charge a LiPo battery. The battery would be wired with a switch to the GND and VCC pins of the Pro Micro.

Things you have to consider are:

  • You have to always be sure that the battery switch is off when connecting the Pro Micro USB port (for programming or running on USB power). Otherwise, you would be feeding 5V to the battery and charger, which could easily damage it.
  • You have to make sure that your display is 5V tolerant or use level shifters to convert the 5V signals from the Pro Micro (when on USB power) to 3.3V for the display.
  • If you add a flash chip, the same 3.3V conversion would be required. You could use one of the regulated flash circuits instead of the lite version for this.
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@MLXXXp your knowledge and willingness to share it is amazing. Great work :laughing:

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I’m not sure what you mean here.
EDIT: The description of the oled says 3-5 volts, so I don’t need any level shifters, right?

I may be completely wrong about this, but as far as I know, level shifting does the same thing as regulators? So there isn’t a need for the regulator portion of the flash cart if there are diodes and resistors doing level shifting?

The ones that handle up to 5 volts usually have an on-board 3.3V regulator. The inexpensive ones use series resistors to limit the current on the signals to handle 5V (which, IMHO, isn’t the best idea but I haven’t seen any complaints about it.

No, you need to regulate the power to the flash chip to 3.3V. You also need level shifting on the signals.

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