0 basic self-study STM32 (wildfire) -- use register to light LED -- Explanation of GPIO function block diagram

What I use is wildfire stm32zet6（ Overbearing development board ） in total 144 One pin , and stm32vet6（ Guider development board ） yes 100 One pin .
Be careful GPIO Not a pin , The pin contains GPIO.
Pins such as VCC,GND,CLK wait

So how to view the function of the pins ？

Find the official data book

pin definition Is the definition of pin
high density high-density


For example, the above two commonly used serial ports

Look from right to left
The first is the protective diode , Take the diode on the upper side as an example , If the input voltage is higher than vdd Diode on , take IO The voltage is clamped at 3.3V+ Range of clamping voltage , This protects the input .
For example ：
If we want to connect a motor , The starting of the motor generates back electromotive force , The diode has not acted for a short time , So as to damage IO.
In addition, the current when starting is also very large .
So we should pay attention to when connecting the motor . Be sure to connect a drive circuit to isolate .

Push pull output ：

What we do is


Every time 4 One bit controls one GPIO

How to output it specifically 0 or 1 Of ？？

Output control register by operation （ODR） To control MOS Output 3.3v or 0v.



It is recommended to understand MOS tube N Tube and P The conduction condition of the tube .
The following figure shows the current flow of output high level , External output , Equivalent to pushing . This is also known as the current infusion , Inject current into the load .

The following figure shows the current flow of output low level , Equivalent to pulling . This is also called pull current .

MOS The internal resistance of the tube is very small , Push pull current can reach 25ma, It's bigger .

The following describes the open drain output
Open drain output can only output low level


What is the meaning of open drain output ？
For example, we pass through IO There's another one out there 5v The peripherals of , We just need an external pull-up VDD Change it to 5V Level matching can be achieved .

Explain , Most of the above uses MOS tube
Complementary signals , Namely 1/0


The output data register corresponds to ODR
We can directly operate the output data register to achieve output 1/0
It can also be set for indirectly / Clear the write operation of the register to control the data output register to output 1/0

bit set / reset register This is it. BSRR
low 16 Position as set Set up 1
high 16 Position as rest clear 0

That is to say, if we are right BS0 and BR0 All written 1, The actual output is in BS0 Shall prevail or 1
There is also a register that can be implemented ODR Output reset operation

Input data register Input data register



This pull-up and pull-down is done by BSRR Register controlled （ In this part of the video, I didn't fully understand the specific implementation methods , Wait until later ）

our IO When the input 3.3v All we can read from the register is 1/0. And Schmidt trigger , It's like a door （ I think it's just “ The threshold ”）, higher than 2v Think it's high level , Output 1, lower than 1.2v It outputs 0
Input multiplexing function

Here we add analog output