STM32 GPIO CSDN creative punch in

GPIO Structure diagram

Push pull output （0-3.3）：

  Enter High level when , At the top of the P-MOS Conduction , At the bottom of the N-MOS end , External output High level  .

Enter Low level when ,N-MOS The pipe is open ,P-MOS end , External output Low level .

When the pin level switches between high and low , Two pipes turn on ,P The tube is responsible for filling the current ,N The tube is responsible for pulling the current , The load capacity and switching speed are greatly improved compared with ordinary methods . The low level of push-pull output is 0 v , The high level is 3.3 v .

Open drain output （0-5）：

In open drain output mode , At the top of the P-MOS The tube is always in the cut-off state . When the input power is low ,P-MOS Pipe cut off ,N-MOS The pipe is open , External output low level .

If the control input is high , be P-MOS The tube is closed ,N-MOS The tube is in the cut-off state , So the pin neither outputs high level , It doesn't output low level either , It's a high resistance state . Output high level if necessary （5V）, A pull-up resistor must be connected externally .

It has “ Line and ” characteristic . in other words , If there are many open drain mode pins connected together , Only if all the pins output high resistance state , The pull-up resistor provides the high level , The voltage of this high level is the voltage of the power supply connected to the external pull-up resistor . If one of the pins is low , Then the line is equivalent to a short circuit to ground , Make the whole line low ,0 v .

  Output data register :

      The above mentioned double MOS The input signal of the tube structure circuit , By GPIO“ Output data register “GPIOx_ODR” Provided , So we can modify it by modifying the value of the output data register GPIO The output level of the pin .

Reuse function output

    “ Reuse function output ” Medium “ Reuse ” Refer to STM32 Other on-chip peripherals of GPIO Pin control , here GPIO The pin is used as part of the peripheral , Second use . From other peripherals “ Multiplexing function output signal ” And GPIO Its own data registers are connected to the double MOS In pipe structure , The ladder structure on the way is used as the switch switching selection .

      For example, we use USART Serial communication , You need to use something GPIO The pin is used as the communication transmission pin , At this time, we can GPIO The pins are configured to USART Serial port multiplexing function , The pin is controlled by the serial peripheral , send data .