Stm32cubemx quadrature encoder

Recently, I encountered the need to obtain the function of orthogonal coding , So come back and study STM32CubeMX Encoder function , It has been updated before STM32 Timer function , However, the principle of the quadrature encoder of the balance car was not clear , Just use the pulse input function directly to get things done , Now I'm paying for my former Youth , But see the existing Encoder The instructions are relatively simple , Therefore, it is considered to contribute to developers , After I research it clearly, I will write a blog .
Coming back to the book , The quadrature encoder is usually installed on the motor , Coaxial with the main shaft of the motor rotor , Some are connected to the encoder through the main shaft to reduce or accelerate the gear set , There are generally two kinds of encoders: grating encoder and magnetic pole encoder , The output pulses of forward rotation and reverse rotation are like the following figure

STM32 It has the function of processing orthogonal pulses , That is, in the timer Encoder Pattern
Specific operation ：

STM32CubeMX To configure

1. open STM32CubeMX, Choose your own chip , Here I use STM32F429IGT6 Take... For example ;

2. Set up the system 、 Basic operation of clock

SYS

RCC

3. Timer settings

Here I choose TIM3,TIM3 Bit Universal timer , There are many general timers for general chips
Combined Channels use Encoder Mode（ Encoder mode ）
After selecting this mode TIM3 Of CH1 and CH2 It becomes an encoder interface , Remember the corresponding two interfaces , Then connect the encoder signal to these two ports , My is PA6 and PA7

The parameter settings below are set according to the requirements , Because I need to record the rising and falling edges of the encoder , So here we choose Encoder Mode TI1 and TI2, This mode will AB The rising and falling edges of both sets of pulses are counted , It's counting 4 Time , Students who do not need to be so precise can put the pre frequency division coefficient （Prescaler） It is amended as follows 4-1, Then pulse detection 4 Pulses will count 1 Time , Filter depends on individual , I use DuPont line to connect directly , distance 10cm No, so I set 0, You can see how to choose STM32 Chinese Reference Manual , Lazy people look at the picture below

4. Serial port settings

To facilitate observation , You need to send the corresponding rotation direction through the serial port , Rotate the count value to the serial port debugging assistant .
Because the chip is only used to send data , There will be no interruption , Directly select asynchronous serial port

5. Finally, configure the clock tree

This is handled by everyone , Each chip is different , Finally let the middle HCLK(MHz) by 72 that will do

6. Project configuration

The development environment I use is Keil5, So in Toolchain/IDE I chose MDK-ARM

When generating code, put Generated files Select the first item in , Otherwise h Document and c Documents are mixed , It's hard to look at

7. Click on the top right corner GENERATE CODE Generate code

Code changes

1. Serial port code modification

For convenience , use printf Function output information , So it needs to be in the serial port /* USER CODE BEGIN 0 */ Add serial port redirection function , As shown below ：

/* USER CODE BEGIN 0 */
#include <stdio.h>
struct __FILE 
{
     
	int handle; 
}; 
FILE __stdout;       
void _sys_exit(int x) 
{
     
	x = x; 
} 
int fputc(int ch, FILE *f)
{
     	
	while((USART1->SR&0X40)==0);// Cycle to send , Until it's sent  
	USART1->DR=(uint8_t)ch;      
	return ch;
}

/* USER CODE END 0 */

2.main.c modify

First, add stdio.h The inclusion of , Convenient for the back printf Output
stay main.c Of /* USER CODE BEGIN Includes */ Add the following code ：

/* USER CODE BEGIN Includes */
#include <stdio.h>
/* USER CODE END Includes */

Then you need several variables , Respectively

Variable name	Variable usage
Direction	Encoder rotation direction
counter	Main function count , be used for printf The timing segment of the function is sent
enc1	Encoder count （0~65535）
enc1_old	Last encoder count （0~65535）
enc2	enc1 Carry of
enc	Final encoder count

Defining variables , stay /* USER CODE BEGIN 1 */ Add the following code

/* USER CODE BEGIN 1 */
  uint8_t Direction;
  uint16_t counter;
  uint16_t enc1 = 0,enc1_old = 0;
  int16_t enc2 = 0;
  int32_t enc;
  /* USER CODE END 1 */

Start encoder interpretation , stay /* USER CODE BEGIN 2 */ Add encoder startup function

/* USER CODE BEGIN 2 */
  HAL_TIM_Encoder_Start(&htim3, TIM_CHANNEL_ALL);
/* USER CODE END 2 */

In circulation , That is to say /* USER CODE BEGIN 3 */ After that, add the reading encoder value function, carry processing function and print output function ：

/* USER CODE BEGIN 3 */
	Direction = __HAL_TIM_IS_TIM_COUNTING_DOWN(&htim3);  
    enc1 = (uint32_t)(__HAL_TIM_GET_COUNTER(&htim3));	// Get the value of the timer 
	if((Direction == 0) &(enc1 < enc1_old))				// The value of positive rotation decreases , Description carry 
	{
    
		enc2++;
	}
	if((Direction == 1) &(enc1 > enc1_old))				// The reverse rotation value becomes smaller , Description borrow 
	{
    
		enc2--;
	}
	enc1_old = enc1;									// to update enc1_old, For the next calculation 
	enc = enc2<<16 | enc1;								// Calculate the total value of the current count , belt +- Number 
	counter++;											// Main function count 
	if(counter>1000)									// The main function runs about 1ms, This is for every 1000ms Send once 
	{
    
		counter = 0;									// The count value is cleared 
		printf("Dir %d, Enc2 %d, Enc1 %d, ENC %d\r\n",Direction,enc2,enc1,enc);// Print relevant count data 
	}
	HAL_Delay(1);
  }
  /* USER CODE END 3 */

At this point, the code has been completely modified , Compile and download to the chip , Wait for wiring test

Wiring test

The encoder I use is 5v A magnetic pole encoder for power supply , But the final interface should be VCC、GND、A、B Four interfaces , At this time, connect as follows

Encoder	STM32
A	TIM3_CH1
B	TIM3_CH2
VCC	5V level
GND	And STM32 Common land

After connecting, you can power on , Open the serial debugging assistant , Connect the serial port 1
You will receive the following data , At this time, you can see the change of the value by turning the encoder

thus , Encoder function has been completed .

		  Good Game！！！！！！

 Next, we will launch a series of sharing about serial port use , Apes in need, please pay attention ！！！！！

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