下面程序有没有懂的，帮我每一句注释一下，谢谢了
unsigned char Function_is_begin = 0;
 unsigned char SettingAngle = 0;
static volatile  unsigned char TempAngle = 0;
 static volatile unsigned int Openloop_PWM = 100;
 static volatile unsigned char Openloop_Step = 5;  
 
void Key1_Press(unsigned char ktype)
 {  
 Function_is_begin = 0;
  PWM_Off();
 
 if(++System_Function > 5)
   System_Function = 0;
  
 switch(System_Function){
 case 0:
  Openloop_Step = 5;
   Openloop_PWM = 100;
  PWM_OutPut(Openloop_PWM);
   //Digit_Set(STEP_POS, 2);
         LCD12864_SetXY(0,2);
   LCD12864_PutNumber(2);
 
  //// Digit_Number(1, Openloop_PWM);
   break;
  case 1:
 // Digit_Off(STEP_POS);
   TempAngle = 45;
   SettingAngle = 45;
  case 2:
  case 3:
  LCD12864_SetXY(0,4);
  LCD12864_PutNumber(TempAngle/10);
   LCD12864_SetXY(0,5);
  LCD12864_PutNumber(TempAngle%10);
//Digit_Set(SETTING_POS0, TempAngle/10);
  //Digit_Set(SETTING_POS1, TempAngle%10);
  // Digit_FlashMode(SETTING_POS0);
   //Digit_FlashMode(SETTING_POS1);
   break;
  case 4:
   break;
  
 case 5:
  //Digit_Off(SETTING_POS0);
   //Digit_Off(SETTING_POS1);
   break;  }   
 //Digit_Set(0, System_Function);  // 显示系统功能编号
  LCD12864_SetXY(0,0);
 LCD12864_PutNumber(System_Function);
 }
void Key2_Press(unsigned char ktype) {
 switch(System_Function){
  case 0:
  switch(Openloop_Step){
    case 1:
    Openloop_Step = 5;
    // Digit_Set(STE.
   // P_POS, 2);
        LCD12864_SetXY(0,2);
   LCD12864_PutNumber(2);
     break;
    case 5:
    Openloop_Step = 10;
   // Digit_Set(STEP_POS, 3);
         LCD12864_SetXY(0,2);
   LCD12864_PutNumber(3);
     break;
    case 10:
    Openloop_Step = 50;
    //Digit_Set(STEP_POS, 4);
          LCD12864_SetXY(0,2);