Android FM模塊學習之三 FM手動調頻

前一章咱們學習了FM的自動調頻，接下來咱們就看看FM手動調頻是如何進行的。若是不清楚FM自動調頻的過程，請打開超連接查看FM搜索頻率流程。

首先來看一下流程圖：

2.滑動刻度盤HorizontalNumberPicker控件在監聽事件裏使用方法valueToFrequency(newVal)

1.長按左右箭頭居中的頻率字符串，彈出FrequencyPickerDialog調頻對話框肯定調用tuneRadio(frequency)調頻。

獲取到頻率

    protected int valueToFrequency(int value) {
           mFrequency = mPrefs.getLowerLimit() + value *
                                 mPrefs.getFrequencyStepSize();
           return mFrequency;
       }

發送一個handler 回調一個tuneRadio(frequency)調頻。

    Runnable mRadioChangeFrequency = new Runnable(){
           public void run() {
               mUpdatePickerValue = false;
               tuneRadio(mFrequency);
           }
       };

3.手動點擊按鈕左右箭頭, 經過監聽調用：

int frequency =FmSharedPreferences.getNextTuneFrequency();

int frequency =FmSharedPreferences.getPrevTuneFrequency();

tuneRadio(frequency);進行調頻

getNextTuneFrequency()方法經過判斷頻率最大限制範圍，後加200（刻度）

getPrevTuneFrequency()方法經過判斷頻率最小限制範圍，後減200（刻度）

調頻方法分析

private void tuneRadio(int frequency)

    private void tuneRadio(int frequency){
          /* Issue the tune command only if tuneCommand is already not active */
          if((mService != null) && (mCommandActive != CMD_TUNE) && isFmOn()) {
             boolean bStatus = false;
             try {
                 bStatus = mService.tune(frequency);
                 if (bStatus) {
                     postTimeoutHandler(CMD_TUNE);
                 }else {
                   if (isFmOn()) {
                      mCommandFailed = CMD_TUNE;
                      Log.e(LOGTAG, "mService.tune failed");
                      showDialog(DIALOG_CMD_FAILED);
                   }
                 }mTunedStation.setName("");
                 mTunedStation.setPI(0);
                 mTunedStation.setPty(0);
                 updateStationInfoToUI();
             }catch (RemoteException e) {
                e.printStackTrace();
             }
          }else {
             Log.e(LOGTAG, "Delayed Tune handler stopped");
          }
       }

經過回調引用類調用FMRadioService類的tune()方法進行調頻

bStatus = mService.tune(frequency);

發送一個廣播鏈接是否超時

postTimeoutHandler(CMD_TUNE);

設置調頻名字，更新FMRadioUI界面信息

mTunedStation.setName("");

mTunedStation.setPI(0);

mTunedStation.setPty(0);

updateStationInfoToUI()

（經過IFMRadioSrevice.aidl通訊機制onbind返回的類的引用調用FMRadioService中的調頻方法）

FMRadioService中的tune方法

public boolean tune(int frequency)

    public boolean tune(int frequency) {
          boolean bCommandSent=false;
          double doubleFrequency = frequency/1000.00;
     
          Log.d(LOGTAG, "tuneRadio:  " + doubleFrequency);
          if (mReceiver != null)
          {
             mReceiver.setStation(frequency);
             bCommandSent = true;
          }
          return bCommandSent;
       }

調用FMReceiver類的setStation方法調頻

public boolean setStation (intfrequencyKHz)

    public boolean setStation (int frequencyKHz) {
          int ret;
     
          mControl.setFreq(frequencyKHz);
          ret = mControl.setStation(sFd);
          if(ret < 0 )
          {
             return false;
          }
          else
          {
             return true;
          }
       }

調用FMRxControls類（FM讀取控制檯信息）設置頻率

mControl.setFreq(frequencyKHz);

設置優化調頻核心指定的頻率

ret = mControl.setStation(sFd);

 

      public int setStation(int fd) {
          Log.d(TAG, "** Tune Using: "+fd);
          int ret = FmReceiverJNI.setFreqNative(fd, mFreq);
          Log.d(TAG, "** Returned: "+ret);
          return ret;
       }

最後調用FmReceiverJNI類

setFreqNative(fd, mFreq); 本地方法 JNI到 cpp文件

    /*native interface */     static jint android_hardware_fmradio_FmReceiverJNI_setFreqNative         (JNIEnv * env, jobject thiz, jint fd, jint freq)     {         int err;         double tune;         struct v4l2_frequency freq_struct;         freq_struct.type = V4L2_TUNER_RADIO;         freq_struct.frequency = (freq*TUNE_MULT/1000);         err = ioctl(fd, VIDIOC_S_FREQUENCY, &freq_struct);         if(err < 0){                 return FM_JNI_FAILURE;         }         return FM_JNI_SUCCESS;     }