I'm sorry for this probably very generic question, but I cannot find a good answer.

I have several STM32(F103C8T6, a.k.a. Blue Pill), which I now power via a ST Link (giving 5V via USB).

The STM32 itself works on 3.3V.

However, I want to use later not USB power, since it should work 'standalone' with an adapter.

Of course it depends on the hardware attached to it, but let's say I don't need much extra (much less than 1A), I think the default way is to:

  • Get a 'generic' 220/240V AC -> 12 V DC adapter
  • Buy a female adapter plug and connect the adapter to it.
  • Connect the wires from the female adapter plug (12V) to a buck converter?
  • Connect the buck converter output to the STM

However, I was wonder:

  • Is it needed to use both an adapter and the converter? Or should I buy a dedicated 5V adapter (which are much less common I think)
  • In case I need a buck converter, I see many types.

The cheapest is e.g. this ... would this work? And in case not, what (kind/type) should I buy?

  • 3
    \$\begingroup\$ A cell-phone charger can be an easy and cheap option. \$\endgroup\$ Jan 6, 2018 at 20:43
  • 2
    \$\begingroup\$ Make your own power supply using LM317 \$\endgroup\$
    – MaNyYaCk
    Jan 8, 2018 at 4:53

1 Answer 1


I see several options:

  1. Use a USB cable and a charger with a USB outlet and connect it to the USB port of your blue pill.

  2. Cut a USB cable in half and solder the red and black wires to the 5V and GND connections of your blue pill, respectively. The blue pill has a voltage regulator to generate 3.3V. Then plug the USB cable into any charger with a USB outlet.

  3. Buy a small power supply that outputs either 5V or 3.3V and connect it to the 5V or 3.3V connector and to the ground of your blue pill. Either solder the connection or - if you have a 3.3V supply - connect it to the 3.3V and GND pins of the ST Link connector.

  4. Do the same as above with a power supply generating a higher voltage and additionally use a buck converter to generate 3.3V.


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