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kasun_duminda92
kasun_duminda92
Associate II
July 26, 2013
Question

Encoder Interface STM32F0 Discovery

  • July 26, 2013
  • 5 replies
  • 2131 views
Posted on July 26, 2013 at 05:16

I have a motor with a quadrature encoder and I want to get the relative (absolute after counting from home position) position. I tried getting the encoder count using an interrupt from one channel of the encoder and checking the state of the other channel. But I found that a lot of counts are missed when the encoders are interfaced this way.

Now I have decided to try the Encoder Interface. The Reference manual says that I don't need 'external interface logic' to connect the encoder so I think I can directly connect the encoder channels to the STM32F0 (the channel voltages shift from 0-3V).  I have seen the Encoder mode example for the STM32F0 but cannot fully understand how to implement it.

What is the maximum value the timer can count upto? Should I set this value?

Which pins correspond to the encoder interface?

What register or variable do I read to get the encoder count?

#encoder-interface #advanced-timers
This topic has been closed for replies.

5 replies

Tesla DeLorean
Tesla DeLorean
Guru
July 26, 2013
Posted on July 26, 2013 at 06:39

Answered in [DEAD LINK /public/STe2ecommunities/mcu/Lists/cortex_mx_stm32/Flat.aspx?RootFolder=/public/STe2ecommunities/mcu/Lists/cortex_mx_stm32/Stm32%20Encoder%20interface&FolderCTID=0x01200200770978C69A1141439FE559EB459D7580009C4E14902C3CDE46A77F0FFD06506F5B&TopicsView=https://my.st.com/public/STe2ecommunities/mcu/Lists/cortex_mx_stm32/AllItems.aspx&currentviews=1601]duplicate.

Here is a blind port to the STM32F0-Discovery 

/* STM32 TIM2 Encoder Decoder (PA.5, PA.2) STM32F0-Discovery sourcer32@gmail.com */
#include ''stm32f0xx.h''
//******************************************************************************
void RCC_Configuration(void)
{
/* TIM2 clock enable */
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);
/* GPIOA clock enable */
RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA, ENABLE);
}
//******************************************************************************
void GPIO_Configuration(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
// Pins selection from STM32F0-Discovery User Manual UM1525
// and Data Manual
/* GPIOA Configuration: TIM2 on PA5 and PA1 */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5 | GPIO_Pin_1;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_2MHz;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL; // Or UP for Open-Collector signals
GPIO_Init(GPIOA, &GPIO_InitStructure);
/* Connect TIM2 pin - Alternate Function Assignment from Table 4 Data Manual */
GPIO_PinAFConfig(GPIOA, GPIO_PinSource5, GPIO_AF_2); // PA5 TIM2_CH1 / TIM2_ETR
GPIO_PinAFConfig(GPIOA, GPIO_PinSource1, GPIO_AF_2); // PA1 TIM2_CH2
}
//******************************************************************************
void TIM2_Configuration(void)
{
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_TimeBaseStructure.TIM_Prescaler = 0;
TIM_TimeBaseStructure.TIM_Period = 0xFFFFFFFF; // Maximal
TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);
// TIM_EncoderMode_TI1: Counter counts on TI1FP1 edge depending on TI2FP2 level.
TIM_EncoderInterfaceConfig(TIM2, TIM_EncoderMode_TI1, TIM_ICPolarity_Rising, TIM_ICPolarity_Rising);
TIM_Cmd(TIM2, ENABLE);
}
//******************************************************************************
int main(void)
{
RCC_Configuration();
GPIO_Configuration();
TIM2_Configuration();
// TIM2->CNT contains current position
while(1); /* Infinite loop */
}

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kasun_duminda92
kasun_duminda92Author
Associate II
August 31, 2013
Posted on August 31, 2013 at 16:13

I was able to make a PID position controller using the counter to get current position.

thanks clive1. Appreciate it.
tuan
tuan
Visitor II
June 13, 2014
Posted on June 13, 2014 at 06:22

Hi you,

Can you share your code about PID controller?

I had problem how can define direction of motor  to increase or decrease number of counter of encoder.

Tesla DeLorean
Tesla DeLorean
Guru
June 13, 2014
Posted on June 13, 2014 at 20:11

I had problem how can define direction of motor  to increase or decrease number of counter of encoder.

I guess because it expects a quadrature type signal where the direction is inferred? If you just have pulses then you're going to want to use an external counter mode, and manual change the up/down configuration of the timer. That or check if the direction is controlled by the state of a direction pin, based on edge(s) of the pulse pin.
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giangxuanhoang
giangxuanhoang
Visitor II
June 24, 2016
Posted on June 24, 2016 at 05:44

Hi Clive1

Here is code which count pulse up/down by step and direction use timer1 but this code was wrote in HAL library, now I want to convert to SPL library but I'm newbie so this is so difficult. Can you give me some advice on this then I will try to modify by myself

#include ''mbed.h''

 

#include ''stm32f4xx.h''

 

#include ''stm32f4xx_hal_tim_ex.h''

 

 

TIM_HandleTypeDef timer;

 

TIM_Encoder_InitTypeDef encoder;

 

 

//direction to PA_9 -- step pulse to PA_8

 

 

int main(){

 

     GPIO_InitTypeDef GPIO_InitStruct;

 

        __TIM1_CLK_ENABLE();

 

        __GPIOA_CLK_ENABLE();

 

        GPIO_InitStruct.Pin = GPIO_PIN_8 | GPIO_PIN_9;

 

        GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;

 

        GPIO_InitStruct.Pull = GPIO_PULLDOWN;

 

        GPIO_InitStruct.Speed = GPIO_SPEED_HIGH;

 

        GPIO_InitStruct.Alternate = GPIO_AF1_TIM1;

 

        HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

 

 

    timer.Instance = TIM1;

 

    timer.Init.Period = 0xffff;

 

    timer.Init.Prescaler = 1;

 

    timer.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;

 

    timer.Init.CounterMode = TIM_COUNTERMODE_UP;

 

 

    encoder.EncoderMode = TIM_ENCODERMODE_TI1;

 

    encoder.IC1Filter = 0x0f;

 

    encoder.IC1Polarity = TIM_INPUTCHANNELPOLARITY_RISING;

 

    encoder.IC1Prescaler = TIM_ICPSC_DIV1;

 

    encoder.IC1Selection = TIM_ICSELECTION_DIRECTTI;

 

 

    encoder.IC2Filter = 0x0f;

 

    encoder.IC2Polarity = TIM_INPUTCHANNELPOLARITY_RISING;   

 

    encoder.IC2Prescaler = TIM_ICPSC_DIV1;

 

    encoder.IC2Selection = TIM_ICSELECTION_INDIRECTTI;

 

 

    HAL_TIM_Encoder_Init(&timer, &encoder);

 

    HAL_TIM_Encoder_Start(&timer,TIM_CHANNEL_1);  

 

 

 

    TIM1->EGR = 1;           // Generate an update event

 

    TIM1->CR1 = 1;           // Enable the counter

 

 

 

while (1) {

 

        int16_t count1;

 

        count1=TIM1->CNT;

 

 

        printf(''%d\r\n'', count1);

 

        wait(1.0);

 

 

};

 

}

 Thanks

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