GPIO of hardware schematic diagram

1、GPIO And gate circuit learning

What are the I / O pins ？

  As input pins

 

 2、 What is a pull-up resistor ？ What is a pull-down resistor ？？

 

3、 see LED Circuit diagram

nLED1-4 Directly connected to the chip , When they are used as output pins , And give low level , Lighting . conversely . Connected to the chip respectively GPB5 6 7 8 Pin . Continue to check the chip manual IO Chapter on ports , See how to configure this pin as an output or input .

  Key circuit diagram analysis

 4、 interrupt

For some chips ,GPIO The pin of can also be used for the interrupt pin .