贴一个ST电机库中对Encoder处理的代码
/*******************************************************************************
* Function Name : ENC_Calc_Rot_Speed
* Description : Compute return latest speed measurement
* Input : None
* Output : s16
* Return : Return motor speed in 0.1 Hz resolution. Since the encoder is
used as speed sensor, this routine will return the mechanical
speed of the motor (NOT the electrical frequency)
Mechanical frequency is equal to electrical frequency/(number
of pair poles).
*******************************************************************************/
s16 ENC_Calc_Rot_Speed(void)
{
s32 wDelta_angle;
u16 hEnc_Timer_Overflow_sample_one, hEnc_Timer_Overflow_sample_two;
u16 hCurrent_angle_sample_one, hCurrent_angle_sample_two;
signed long long temp;
s16 haux;
if (!bIs_First_Measurement)
{
// 1st reading of overflow counter
hEnc_Timer_Overflow_sample_one = hEncoder_Timer_Overflow;
// 1st reading of encoder timer counter
hCurrent_angle_sample_one = ENCODER_TIMER->CNT;
// 2nd reading of overflow counter
hEnc_Timer_Overflow_sample_two = hEncoder_Timer_Overflow;
// 2nd reading of encoder timer counter
hCurrent_angle_sample_two = ENCODER_TIMER->CNT;
// Reset hEncoder_Timer_Overflow and read the counter value for the next
// measurement
hEncoder_Timer_Overflow = 0;
haux = ENCODER_TIMER->CNT;
if (hEncoder_Timer_Overflow != 0)
{
haux = ENCODER_TIMER->CNT;
hEncoder_Timer_Overflow = 0;
}
if (hEnc_Timer_Overflow_sample_one != hEnc_Timer_Overflow_sample_two)
{ //Compare sample 1 & 2 and check if an overflow has been generated right
//after the reading of encoder timer. If yes, copy sample 2 result in
//sample 1 for next process
hCurrent_angle_sample_one = hCurrent_angle_sample_two;
hEnc_Timer_Overflow_sample_one = hEnc_Timer_Overflow_sample_two;
}
if ( (ENCODER_TIMER->CR1 & TIM_CounterMode_Down) == TIM_CounterMode_Down)
{// encoder timer down-counting
wDelta_angle = (s32)(hCurrent_angle_sample_one - hPrevious_angle -
(hEnc_Timer_Overflow_sample_one) * (4*ENCODER_PPR));
}
else
{//encoder timer up-counting
wDelta_angle = (s32)(hCurrent_angle_sample_one - hPrevious_angle +
(hEnc_Timer_Overflow_sample_one) * (4*ENCODER_PPR));
}
// speed computation as delta angle * 1/(speed sempling time)
temp = (signed long long)(wDelta_angle * SPEED_SAMPLING_FREQ);
temp *= 10; // 0.1 Hz resolution
temp /= (4*ENCODER_PPR);
} //is first measurement, discard it
else
{
bIs_First_Measurement = FALSE;
temp = 0;
hEncoder_Timer_Overflow = 0;
haux = ENCODER_TIMER->CNT;
// Check if Encoder_Timer_Overflow is still zero. In case an overflow IT
// occured it resets overflow counter and wPWM_Counter_Angular_Velocity
if (hEncoder_Timer_Overflow != 0)
{
haux = ENCODER_TIMER->CNT;
hEncoder_Timer_Overflow = 0;
}
}
hPrevious_angle = haux;
return((s16) temp);
}
写得很长，看着很酷，不过很遗憾，实际使用时不如MicroChip Manul中的几句话好用
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