Question

我已经下载了Lollipop 5.0的AOSP源代码。在api级别21中，在蓝牙低能量扫描设置下，有三种扫描设备的选项 - SCAN_MODE_BALANCED, SCAN_MODE_LOW_LATENCY, SCAN_MODE_LOW_POWER。是基于不同的扫描间隔和扫描窗口值？如果是这样，我在哪里可以找到在源代码目录中为这些宏定义的值。

Answer 1

在greping关键字“SCAN_MODE_BALANCED”时，我在http://androidxref.com/5.0.0_r2/xref/packages/apps/Bluetooth/src/com/android/bluetooth/gatt/ScanManager.java中找到了以下值：

    /**
     * Scan params corresponding to regular scan setting
     */
    private static final int SCAN_MODE_LOW_POWER_WINDOW_MS = 500;
    private static final int SCAN_MODE_LOW_POWER_INTERVAL_MS = 5000;
    private static final int SCAN_MODE_BALANCED_WINDOW_MS = 2000;
    private static final int SCAN_MODE_BALANCED_INTERVAL_MS = 5000;
    private static final int SCAN_MODE_LOW_LATENCY_WINDOW_MS = 5000;
    private static final int SCAN_MODE_LOW_LATENCY_INTERVAL_MS = 5000;

    /**
     * Scan params corresponding to batch scan setting
     */
    private static final int SCAN_MODE_BATCH_LOW_POWER_WINDOW_MS = 1500;
    private static final int SCAN_MODE_BATCH_LOW_POWER_INTERVAL_MS = 150000;
    private static final int SCAN_MODE_BATCH_BALANCED_WINDOW_MS = 1500;
    private static final int SCAN_MODE_BATCH_BALANCED_INTERVAL_MS = 15000;
    private static final int SCAN_MODE_BATCH_LOW_LATENCY_WINDOW_MS = 1500;
    private static final int SCAN_MODE_BATCH_LOW_LATENCY_INTERVAL_MS = 5000;

同时签出ScanManager.ScanNative.configureRegularScanParams（）。根据扫描设置（scanWindow，scanInterval，ScanSettings.SCAN_MODE_LOW_POWER）设置两个参数ScanSettings.SCAN_MODE_BALANCED和ScanSettings.SCAN_MODE_LOW_LATENCY，转换为BLE单位，然后传递给gattSetScanParametersNative （）。

希望这有帮助。

Answer 2

我不确定这是否准确，或者您是否可以使用它来查找所需的值，但我找到了一些code from Google regarding scanning settings：

  // Constants for Scan Cycle
  // Low Power: 2.5 minute period with 1.5 seconds active (1% duty cycle)
  /* @VisibleForTesting */ static final int LOW_POWER_IDLE_MILLIS = 148500;
  /* @VisibleForTesting */ static final int LOW_POWER_ACTIVE_MILLIS = 1500;

  // Balanced: 15 second period with 1.5 second active (10% duty cycle)
  /* @VisibleForTesting */ static final int BALANCED_IDLE_MILLIS = 13500;
  /* @VisibleForTesting */ static final int BALANCED_ACTIVE_MILLIS = 1500;

  // Low Latency: 1.67 second period with 1.5 seconds active (90% duty cycle)
  /* @VisibleForTesting */ static final int LOW_LATENCY_IDLE_MILLIS = 167;
  /* @VisibleForTesting */ static final int LOW_LATENCY_ACTIVE_MILLIS = 1500;

Android AOSP - android源代码中扫描间隔和扫描窗口的定义

2 个答案: