V39按键分析

说明

master的电视芯片V39的按键处理分析

不同的按键按下去读到不同的ad值，反过来根据按键值就可以得出是哪个按键。
ad值有一定范围。程序里一般是该值的容忍度，认为只要在容忍度范围内就是这个按键的值。

过程为为检测到按下 开始记录 检测到抬起后，检测记录的按键值是否一样。

探测到按键值后，全局标记g_bKeyDetect会被置位，handler处理函数处理后再清零。这就像生产者和消费者。

按键产生函数有BUG，可能产生串键。看着改吧

具体说明

1. AD值集合

下面代码是按键会触发的AD值集合。

BYTE code tADCKeyLevel[ADC_KEY_CHANNEL_NUM][8] =
{
  {KEY1_AD_L0,KEY1_AD_L1,KEY1_AD_L2,KEY1_AD_L3,KEY1_AD_L4,KEY1_AD_L5,KEY1_AD_L6,KEY1_AD_L7},
  {KEY2_AD_L0,KEY2_AD_L1,KEY2_AD_L2,KEY2_AD_L3,KEY2_AD_L4,KEY2_AD_L5,KEY2_AD_L6,KEY2_AD_L7},
};

如

#define KEY1_AD_L0                      0x01
#define KEY1_AD_L1                      0x26
#define KEY1_AD_L2                      0x4D
#define KEY1_AD_L3                      0x74
#define KEY1_AD_L4                      0x9B
#define KEY1_AD_L5                      0xB9
#define KEY1_AD_L6                      0xD8
#define KEY1_AD_L7                      0xEF

2. AD值的容忍度

#define KEY_AD_DELTA                    0x05    // tolerance

3. AD值的获取

if (ucAdcLv < (tADCKeyLevel[ucAdcChannel][0] + KEY_AD_DELTA))
        return tADCKeyLevel[ucAdcChannel][0];
    else if ((tADCKeyLevel[ucAdcChannel][1]-KEY_AD_DELTA) < ucAdcLv && ucAdcLv < (tADCKeyLevel[ucAdcChannel][1]+KEY_AD_DELTA))
        return tADCKeyLevel[ucAdcChannel][1];
...

4. 将AD值转换为按键

if(KeyValue<=KEY1_AD_L0)
       KeyStatus |= tADCKeyFlag[0][0];
 else if(KeyValue<=KEY1_AD_L1)
       KeyStatus |= tADCKeyFlag[0][1];
...

按键定义如下

#define ADC_KEY_1_L0_FLAG               KEY_POWER       
#define ADC_KEY_1_L1_FLAG               KEY_DOWN            
#define ADC_KEY_1_L2_FLAG               KEY_UP           
#define ADC_KEY_1_L3_FLAG               KEY_RIGHT        
#define ADC_KEY_1_L4_FLAG               KEY_LEFT         
#define ADC_KEY_1_L5_FLAG               KEY_MENU         
#define ADC_KEY_1_L6_FLAG               KEY_SOURCE 
#define ADC_KEY_1_L7_FLAG               KEY_PIP

typedef enum _KeyScanType
{
    KEY_NOTHING = 0x00,
    KEY_MENU   = _BIT0,
    KEY_UP     = _BIT1,
    KEY_DOWN   = _BIT2,
    KEY_LEFT   = _BIT3,
    KEY_RIGHT  = _BIT4,
    KEY_SOURCE = _BIT5,
    KEY_PIP    = _BIT6,
    KEY_POWER  = _BIT7,
    //KEY_RELOAD_EEPROM = _BIT1 | _BIT2 | _BIT7
} KeyScanType;

5. 按键产生函数

void keyDetectPoll(void)
{
    KeyScanType ucStatusBff; // status buffer

    if (g_ucKeyCounter == 0) // check counter
    {

    
       #if 0// KEY_USE_INTERRUPT
        ucStatusBff = IsrKeyScanStatus(); // scan key status
       #else
        ucStatusBff = keyScanStatus(); // scan key status
       #endif
        if (ucStatusBff == g_LastKeyStatus) // match last
        {
            if (g_bKeyDetect) // check key busy
                ;
            else if (g_LastKeyStatus) // check key pressed
            {
                if (g_KeyCode == g_LastKeyStatus) // check repeat
                {
                    if (g_bKeyCheckRepeat) // need to repeat
                    {
                        if (g_bKey1stRepeat)
                        {
                            g_ucKeyDebounce++;
                            if (g_ucKeyDebounce==KEY_DEBOUNCE_REPEAT)
                            {
                                g_ucKeyDebounce = 0;
                                g_bKey1stRepeat = 0;
                                g_bKeyDetect = 1; // detect key
                            }
                        }
                        else
                        {
                            g_bKeyRepeat = 1;
                            g_ucKeyDebounce++;
                            if ((!g_bKeypad_FastRepeat && g_ucKeyDebounce==KEY_DEBOUNCE_REPEAT)
                              || (g_bKeypad_FastRepeat && g_ucKeyDebounce==KEY_DEBOUNCE_FAST))
                            {
                                g_ucKeyDebounce = 0;
                                g_bKeyDetect = 1; // detect key
                            }
                        }
                    }
                }
                else // new key pressed
                {
                    g_KeyCode = g_LastKeyStatus;
                    g_bKeyDetect = 1; // detect key
                    g_bKeyRepeat = 0;
                    g_bKey1stRepeat = 1;
                    g_bKeyCheckRepeat = 0;
                    g_ucKeyDebounce = 0;
                    g_bKeypad_FastRepeat = 0;
                #if ENABLE_MEDIA
                    if(ucStatusBff == KEY_MENU)
                        g_bJPKeyEventFlag = 1;
                #endif
                }
            }
            else // no key pressed
            {
                g_KeyCode = KEY_NOTHING; // reset key code
            }
        }
        else // different
        {
            g_LastKeyStatus = ucStatusBff; // refresh key status
            g_bKeyRepeat = 0;
            g_bKey1stRepeat = 1;
            g_bKeyCheckRepeat = 0;
            g_ucKeyDebounce = 0;
            g_bKeypad_FastRepeat = 0;
        #if ENABLE_MEDIA
            if(ucStatusBff == KEY_MENU)
                g_bJPKeyEventFlag =1;
        #endif
        }
        g_ucKeyCounter = KEY_DEBOUNCE_TIME; // next time counter
    }
}