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In addition to your “Blue Pill,” you will also need a 3.3V USB to serial converter. I used a SparkFun Serial Basic configured for 3.3V. Only the power, TX and RX pins will be used, so you should be able to use a standard FTDI board as well.
Some serial converter boards put out 5V as VCC even when set to 3.3V mode. Be careful!
Applying 5V to the 3.3V main supply line of Blue Pill will kill it.
There is a 5V input on the Blue Pill and a USB connector that can power the board from 5V. These go through a small 3.3V regulator.
Lots of pins on the STM32F103C8T6 are purported to be 5V tolerant, but the main DC isn't! I don't know if TX/RX are.
GNDpins of the Blue Pill (or
GNDif your serial converter board puts out 5V even in 3.3V mode).
A9and TX to
Under the Tools menu, make the following selections:
To put the device into “use” mode, move the top jumper back to 0 (left) position.