STM32 learning notes on quadrature encoder interface

I recently worked on a project, the main control chip is STM32RBT6, and I need to use a grating ruler. It originally came with a controller, and the data of the grating ruler can be read through the controller's 232, but this controller is too large to fit in the device, so I considered making one myself. I saw many useful CPLD solutions on the Internet, and later I accidentally discovered that the timer of stm32 can be configured as an encoder, which made me very

happy. I was very happy, but suddenly I found that the timer of stm32 is 16 bits, and the count of my grating ruler will exceed 65535, so I consulted several experts on the 21ic forum, and finally determined the solution. The

working process is to configure TIM3 to orthogonal encoder mode, and set a 10ms interrupt, read the count value every 10ms, and the premise of 10ms is that the counter does not overflow within 10ms (thanks to lxyppc of 21ic for this idea) )

The following is some code: (These codes are modified from ST official routines, but my project uses the V3 firmware library, and their routines seem to be 0.3, so some places have been changed)
The following is to initialize TIM3 to quadrature encoder mode
void ENC_Init(void)
{
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_ICInitTypeDef TIM_ICInitStructure;

/* Encoder unit connected to TIM3, 4X mode */    
GPIO_InitTypeDef GPIO_InitStructure;
NVIC_InitTypeDef NVIC_InitStructure;

/* TIM3 clock source enable */
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);
/* Enable GPIOA, clock */
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);

GPIO_StructInit(&GPIO_InitStructure);
/* Configure PA.06,07 as encoder input */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6 | GPIO_Pin_7;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
GPIO_Init(GPIOA, &GPIO_InitStructure);

/* Enable the T IM3 Update Interrupt */
NVIC_InitStructure.NVIC_IRQChannel = TIM3_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = TIMx_PRE_EMPTION_PRIORITY;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = TIMx_SUB_PRIORITY;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);

/* Timer configuration in Encoder mode */
TIM_DeInit(ENCODER_TIMER);
TIM_TimeBaseStructInit(&TIM_TimeBaseStructure);

TIM_TimeBaseStructure.TIM_Prescaler = 0x0; // No prescaling 
TIM _TimeBaseStructure.TIM_Period = ENCODER_TIM_PERIOD; 
TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;   
TIM_TimeBaseInit(ENCODER_TIMER, &TIM_TimeBaseStructure);

TIM_EncoderInterfaceConfig(EN CODER_TIMER, TIM_EncoderMode_TI12, 
                             TIM_ICPolarity_Rising, TIM_ICPolarity_Rising);
TIM_ICStructInit(&TIM_ICInitStructure);
TIM_ICInitStructure.TIM_ICFilter = ICx_FILTER;
TIM_ICInit(ENCODER_TIMER, &TIM_ICInitStructure);

// Clear all pending interrupts
TIM_ClearFlag(ENCODER_TIMER, TIM_FLAG_Update);
TIM_ITConfig(ENCODER_TIMER, TIM_IT_Update, ENABLE);
//Reset counter
TIM2->CNT = COUNTER_RESET;

// ENC_Clear_Speed_Buffer();

TIM_Cmd(ENCODER_TIMER, ENABLE); 
}
The following is to obtain a count value, this algorithm comes from lxyppc, you can avoid the situation of exceeding 16 bits. For details, see the discussion at http://bbs.21ic.com/viewthread.php?tid=110623

s16 ENC_Get_Electrical_Angle(void)
{
static u16 lastCount = 0;
u16 curCount = ENCODER_TIMER->CNT;
s32 dAngle = curCount - lastCount;
if(dAngle >= MAX_COUNT){
    dAngle -= ENCODER_TIM_PERIOD;
}else if(dAngle < -MAX_COUNT){
    dAngle += ENCODER_TIM_PERIOD;
}
lastCount = curCount;
return (s16)dAngle; 
}

The following is the system tick initialization and interrupt function
void TB_Init(void)
{   
/* Setup SysTick Timer for 10 msec interrupts */
if (SysTick_Config(SystemFrequency / 100))
{ 
    /* Capture error */ 
    while (1);
}
}

void SysTick_Handler(void)
{   
/*if (hTimebase_display_500us != 0) 
{
    hTimebase_display_500us --;
}
   */
if (hSpeedMeas_Timebase_500us !=0)
{
    hSpeedMeas_Timebase_500us--;
}
else
{
    hSpeedMeas_Timebase_500us = SPEED_SAMPLING_TIME;

    CurrentCount += ENC_Get_Electrical_Angle();
        
    //ENC_Calc_Average_Speed ​​must be called ONLY every SPEED_MEAS_TIMEBASE ms
    //ENC_Calc_Average_Speed();    
}
}
The above code has passed the test, the firmware library version is: V3.1.2
ST official routines and Chinese documentation: http://www.stmicroelectronics.com.cn/stonline/mcu/images/STM32F10xxx_Encoder_AN%28CH%29.pdf
http://images.stmicroelectronics.com.cn/stonline/mcu/images/STM32F10xxx_Encoder_AN(CH).zip

Finally, I have to complain, why doesn’t ST make the timer 32-bit? Can it increase the cost by 1 cent?