stm32定时器的编码器模式例程中的测速没看懂····求教···

亲亻尔嘴

[mw_shl_code=c,true]/******************************************************************************* * Function Name : ENC_Calc_Rot_Speed * Description : Compute return latest speed measurement * Input : None * Output : s16 * Return : Return the speed in 0.1 Hz resolution. *******************************************************************************/ 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); } [/mw_shl_code]

这段函数实在是没理解···
再附上完整例程。

亲亻尔嘴

 例程中使用TIM3更新中断来记录溢出次数，在中断服务中只有一句 

[mw_shl_code=c,true]hEncoder_Timer_Overflow++;[/mw_shl_code]

紧接着就是连续两次取出 溢出次数 和 CNT的值：

[mw_shl_code=c,true] // 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; [/mw_shl_code]

再接着就是：

[mw_shl_code=c,true]hEncoder_Timer_Overflow = 0; haux = ENCODER_TIMER->CNT; if (hEncoder_Timer_Overflow != 0) { haux = ENCODER_TIMER->CNT; hEncoder_Timer_Overflow = 0; }[/mw_shl_code]

这是不是说在运行 [mw_shl_code=c,true]hEncoder_Timer_Overflow = 0;有可能在下一句就发生溢出中断，所以需要再次判断，并将其清0.[/mw_shl_code] [mw_shl_code=c,true]然后就是判断刚刚两次取出的值：[/mw_shl_code] [mw_shl_code=c,true]

[mw_shl_code=c,true] 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; }[/mw_shl_code]

如果取出第一次的值之后发生了溢出中断，就会进入上述if语句，将第一次的值舍弃。[/mw_shl_code] [mw_shl_code=c,true]下面这个处理就不明白了：[/mw_shl_code] [mw_shl_code=c,true]

[mw_shl_code=c,true] 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)); }[/mw_shl_code] // 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);

[/mw_shl_code] [mw_shl_code=c,true] [/mw_shl_code]

正点原子

帮顶....

亲亻尔嘴

回复【3楼】正点原子:
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别只帮顶啊 原子大哥，抽空帮忙看看呀····

gaoxiaohu110

很久以前的帖子了，不知道楼主闹明白没有，最近我也在研究编码器的问题，发现官方的例程！Return the speed in 0.1 Hz.我的理解就是编码器频率，x60就是转速， 但是这个函数  真心看不明白

whileandwhen

gaoxiaohu110 发表于 2016-5-4 23:27
很久以前的帖子了，不知道楼主闹明白没有，最近我也在研究编码器的问题，发现官方的例程！Return the speed ...

同样在研究编码器问题 共同探讨一下吧

gaoxiaohu110

whileandwhen 发表于 2016-5-6 16:33
同样在研究编码器问题 共同探讨一下吧

ok!大家共同探讨一下，我就不明白这个速度的采样时间
#define SPEED_SAMPLING_TIME  9     // (9+1)*500usec = 10msec
SysTick 500usec中断一次，为什么(9+1)*500usec = 10msec；这是怎么算的
另外，如果正确的话为什么要9+1呢？

陈孤帆

编码器的问题可以问我·QQ 416754707大家一起交流下~！

YIN零

各位大神，编码器能不能同时测速和记里程啊？