How to choose the resistor in the brushless ESC drive circuit?

The main function of the triode here is to enhance the driving ability; the base resistance is too large to drive the triode, too small will affect the life of the triode, check the parameters of the triode you choose, and calculate by yourself, it is OK to be able to turn on the triode with a certain margin.

Your signal coming out of the single-chip microcomputer has a weak driving ability, which may be only a few milliamps. If you add a triode drive, it can reach hundreds of milliamps. If you drive a P-channel tube, your resistance is too small and the current is large, of course, it will affect the life.

The transmitting junction is positively biased, and the collector junction is reversely biased to work in the amplification region, otherwise, if the collector junction is forward biased, it will work in the saturation region.