Solved
High speed error with encoder, STM32F103
Hello,
We are using an encoder ( https://www.andymark.com/products/redline-encoder-kit ) with 4096 CPR and are trying to measure speed and direction of a motor with an STM32F103. However, we cannot read stable values and in high frequencies we cannot read at all. Currently, our MCU is working on 72 MHz frequency and in TIM2 we are using the Encoder mode with interrupt. (Prescaler value=0, Counter period value=65535)
Should we use the DMA as well? Would it make any difference? Do you have any suggestions on what improvements we could make to our system?
Below is our snippet of user code regarding the issue.
Thanks in advance.
*EDIT: Updated the prescaler and counter period value
typedef struct encoderStruct {
uint32_t counter_u32;
_Bool measuredDirection_bool;
float measuredSpeed_f32;
}ENCODER_HandleTypeDef;
// ***
void Measure_Speed(TIMER_HandleTypeDef *timer, FLAG_HandleTypeDef *flag, ENCODER_HandleTypeDef *encoder){
if(TIM2->CR1 == 1) {
encoder->measuredDirection_bool = 0;
encoder->counter_u32 = (uint32_t)(TIM2->CNT);
if(timer->velocityCalculator_u16 > VELOCITY_TIME) {
TIM2->CNT = 0;
encoder->measuredSpeed_f32 = ((float)encoder->counter_u32 / ENCODER_PULS) * 60.0;
timer->velocityCalculator_u16 = 0;
flag->LED.motorForward_bit = 1;
flag->LED.motorBackward_bit = 0;
}
} else if(TIM2->CR1 == 17) {
encoder->measuredDirection_bool = 1;
encoder->counter_u32 = 65535 - (uint32_t)TIM2->CNT;
if(timer->velocityCalculator_u16 > VELOCITY_TIME) {
TIM2->CNT = 65535;
encoder->measuredSpeed_f32 = ((float)encoder->counter_u32 / ENCODER_PULS) * 60.0;
timer->velocityCalculator_u16 = 0;
flag->LED.motorForward_bit = 0;
flag->LED.motorBackward_bit = 1;
}
}
}
//***
HAL_TIM_Encoder_Start_IT(&htim2, encoderA_Pin);
HAL_TIM_Encoder_Start_IT(&htim2, encoderB_Pin);