1 background
Because the designed thing is a motor, but the output current of the stm32 port is too small, so the relay is used for control. Through the actual wiring test, it is found that the IO port of the MCU cannot drive the relay. When the relay is connected to the IO port, the port voltage will drop to 2.2V. Left and right, the relay can no longer be driven.
2 circuit design
Therefore, in order to be able to drive the relay, the circuit is redesigned, and the relay is driven by the triode, and the relay can be driven by the actual test. The circuit is shown below.
R1 takes 1K