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最近有个需求：检测琴键的按键速度。一个琴键有两个轻触开关，检测这两个轻触开关的时差就能实现按键速度。

用GD32F350CPU，50us定时扫描键盘，把按下的按键对应的速度通过USB发出去，裸机代码只做这两件事情。

实际测试扫描键盘的时间不到40us，现在的问题是：当同时按下全部的按键时，有时会扫描不到部分按键。同时按下的按键数比较少时，就不会发生上述问题。

洗耳恭听大家的建议和指导！

代码如下：

void Martrix_KB_Handle(void)

{

uint8 idx;

for(idx=0;idx

{

switch (Keys[idx].State)

{

case State_NoteOFF:

if ( PRE_NOTE_ON == Keys[idx].Cur_KeyStatus )

{

Keys[idx].State = State_PreNoteON;

}

break;

case State_PreNoteON://Front键先按下，velocity开始计数

Keys[idx].Note_Velocity.u32_velocity++;

if ( NOTE_ON == Keys[idx].Cur_KeyStatus )

{

Keys[idx].State = State_NoteON;

#ifdef JLINK_RTT_DEBUG

SEGGER_RTT_printf(0,"%2d: ON%5d\r\n",idx+1,Keys[idx].Note_Velocity.u32_velocity);

#endif

if(Sys_Flag.Upload_Enable)

{

ON_FIFO.Note_Buffer[ON_FIFO.Idx_IN].num = idx;

ON_FIFO.Note_Buffer[ON_FIFO.Idx_IN].velocity.u32_velocity = Keys[idx].Note_Velocity.u32_velocity;

ON_FIFO.Idx_IN++;

if(ON_FIFO.Idx_IN==Buffer_Size) ON_FIFO.Idx_IN = 0;

}

Keys[idx].Note_Velocity.u32_velocity = 0;

}

else if ( NOTE_OFF == Keys[idx].Cur_KeyStatus ) //按下一半就松开的情况

{

Keys[idx].Note_Velocity.u32_velocity = 0;

Keys[idx].State = State_NoteOFF;

}

break;

case State_NoteON:

if ( PRE_NOTE_OFF == Keys[idx].Cur_KeyStatus )

{

Keys[idx].State = State_PreNoteOFF;

}

break;

case State_PreNoteOFF:

Keys[idx].Note_Velocity.u32_velocity++;

if ( NOTE_OFF == Keys[idx].Cur_KeyStatus )

{

Keys[idx].State = State_NoteOFF;

#ifdef JLINK_RTT_DEBUG

SEGGER_RTT_printf(0,"%2d:OFF%5d\r\n",idx+1,Keys[idx].Note_Velocity.u32_velocity);

#endif

if(Sys_Flag.Upload_Enable)

{

OFF_FIFO.Note_Buffer[OFF_FIFO.Idx_IN].num = idx;

OFF_FIFO.Note_Buffer[OFF_FIFO.Idx_IN].velocity.u32_velocity = Keys[idx].Note_Velocity.u32_velocity;

OFF_FIFO.Idx_IN++;

if(OFF_FIFO.Idx_IN==Buffer_Size) OFF_FIFO.Idx_IN = 0;

}

Keys[idx].Note_Velocity.u32_velocity = 0;

}

break;

default:

break;

}

}

}

void Martrix_KB_Handle(void)

{

uint8 idx;

for(idx=0;idx

{

switch (Keys[idx].State)

{

case State_NoteOFF:

if ( PRE_NOTE_ON == Keys[idx].Cur_KeyStatus )

{

Keys[idx].State = State_PreNoteON;

}

break;

case State_PreNoteON://Front键先按下，velocity开始计数

Keys[idx].Note_Velocity.u32_velocity++;

if ( NOTE_ON == Keys[idx].Cur_KeyStatus )

{

Keys[idx].State = State_NoteON;

#ifdef JLINK_RTT_DEBUG

SEGGER_RTT_printf(0,"%2d: ON%5d\r\n",idx+1,Keys[idx].Note_Velocity.u32_velocity);

#endif

if(Sys_Flag.Upload_Enable)

{

ON_FIFO.Note_Buffer[ON_FIFO.Idx_IN].num = idx;

ON_FIFO.Note_Buffer[ON_FIFO.Idx_IN].velocity.u32_velocity = Keys[idx].Note_Velocity.u32_velocity;

ON_FIFO.Idx_IN++;

if(ON_FIFO.Idx_IN==Buffer_Size) ON_FIFO.Idx_IN = 0;

}

Keys[idx].Note_Velocity.u32_velocity = 0;

}

else if ( NOTE_OFF == Keys[idx].Cur_KeyStatus ) //按下一半就松开的情况

{

Keys[idx].Note_Velocity.u32_velocity = 0;

Keys[idx].State = State_NoteOFF;

}

break;

case State_NoteON:

if ( PRE_NOTE_OFF == Keys[idx].Cur_KeyStatus )

{

Keys[idx].State = State_PreNoteOFF;

}

break;

case State_PreNoteOFF:

Keys[idx].Note_Velocity.u32_velocity++;

if ( NOTE_OFF == Keys[idx].Cur_KeyStatus )

{

Keys[idx].State = State_NoteOFF;

#ifdef JLINK_RTT_DEBUG

SEGGER_RTT_printf(0,"%2d:OFF%5d\r\n",idx+1,Keys[idx].Note_Velocity.u32_velocity);

#endif

if(Sys_Flag.Upload_Enable)

{

OFF_FIFO.Note_Buffer[OFF_FIFO.Idx_IN].num = idx;

OFF_FIFO.Note_Buffer[OFF_FIFO.Idx_IN].velocity.u32_velocity = Keys[idx].Note_Velocity.u32_velocity;

OFF_FIFO.Idx_IN++;

if(OFF_FIFO.Idx_IN==Buffer_Size) OFF_FIFO.Idx_IN = 0;

}

Keys[idx].Note_Velocity.u32_velocity = 0;

}

break;

default:

break;

}

}

}