Android：通过BLE发送大于20个字节的数据
通过连接到外部BLE设备，我最多可以发送20个字节的数据。如何发送大于20个字节的数据。我已经读到我们必须将数据分段或将特征拆分为所需的部分。如果我假设我的数据是32字节，你能否告诉我我需要在代码中进行的更改才能使其正常工作？以下是我的代码中必需的摘录：
public boolean send(byte[] data) { if (mBluetoothGatt == null || mBluetoothGattService == null) {
Log.w(TAG, "BluetoothGatt not initialized");
return false;
}
BluetoothGattCharacteristic characteristic =
mBluetoothGattService.getCharacteristic(UUID_SEND);
if (characteristic == null) {
Log.w(TAG, "Send characteristic not found");
return false;
}
characteristic.setValue(data);
characteristic.setWriteType(BluetoothGattCharacteristic.WRITE_TYPE_NO_RESPONSE);
return mBluetoothGatt.writeCharacteristic(characteristic);
}
这是我用于发送数据的代码。在以下onclick事件中使用“发送”功能。
sendValueButton = (Button) findViewById(R.id.sendValue); sendValueButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String text = dataEdit.getText().toString();
yableeService.send(text.getBytes());
}
});
当String text大于20个字节时，则仅接收前20个字节。如何纠正呢？
为了测试发送多个特征，我尝试了以下操作：
sendValueButton = (Button) findViewById(R.id.sendValue);sendValueButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String text = "Test1";
yableeService.send(text.getBytes());
text = "Test2";
yableeService.send(text.getBytes());
text = "Test3";
yableeService.send(text.getBytes());
}
});
但是我只收到“ Test3”，即最后一个特征。我犯了什么错误？我是BLE新手，所以请忽略任何幼稚
编辑：
在为以后查看此内容的任何人接受答案之后。
有两种方法可以完成此操作。1.拆分数据并像所选答案一样循环编写。2.拆分数据并使用回调（即）进行写入onCharacterisitcWrite()。如果在编写过程中出现任何错误，这将使你免于错误。
但是，如果你只是在写而不等待固件的响应，则两次写之间最重要的是使用a Thread.sleep(200)。这将确保你的所有数据都能到达。没有sleepI，我总是得到最后一个数据包。如果你注意到已接受的答案，他也会sleep在两者之间使用。
回答：
BLE最多允许你传输20个字节。
如果要发送20个以上的字节，则应定义数组byte[]以包含所需的数据包数量。
如果你要发送少于160个字符（160个字节），以下示例可以很好地工作。
p / s：根据需要编辑以下内容。不要完全跟随我。
实际上，当我们使用BLE时，移动端和固件端需要设置密钥（例如0x03...）来定义双方之间的连接门。
这个想法是：
当我们继续传输数据包时，不是最后一个。门是
byte[1] = 0x01。如果我们发送最后一个，则门为
byte[1] = 0x00。
数据构造（20字节）：
1– Byte 1定义Gate ID：例如。消息门ID byte[0] = 0x03。
2- Byte 2定义recognization：是最后一个数据包0x00还是继续发送数据包0x01。
3- Byte 3（在消除Byte 1＆之后，应为18个字节Byte 2）-在此处附加消息内容。
在阅读下面的代码之前，请先了解我的逻辑。
下面是发送带有许多数据包的消息的示例，每个数据包是一个大小为20字节的数组。
private void sendMessage(BluetoothGattCharacteristic characteristic, String CHARACTERS){ byte[] initial_packet = new byte[3];
/**
* Indicate byte
*/
initial_packet[0] = BLE.INITIAL_MESSAGE_PACKET;
if (Long.valueOf(
String.valueOf(CHARACTERS.length() + initial_packet.length))
> BLE.DEFAULT_BYTES_VIA_BLE) {
sendingContinuePacket(characteristic, initial_packet, CHARACTERS);
} else {
sendingLastPacket(characteristic, initial_packet, CHARACTERS);
}
}
private void sendingContinuePacket(BluetoothGattCharacteristic characteristic,
byte[] initial_packet, String CHARACTERS){
/**
* TODO If data length > Default data can sent via BLE : 20 bytes
*/
// Check the data length is large how many times with Default Data (BLE)
int times = Byte.valueOf(String.valueOf(
CHARACTERS.length() / BLE.DEFAULT_BYTES_IN_CONTINUE_PACKET));
Log.i(TAG, "CHARACTERS.length() " + CHARACTERS.length());
Log.i(TAG, "times " + times);
// TODO
// 100 : Success
// 101 : Error
byte[] sending_continue_hex = new byte[BLE.DEFAULT_BYTES_IN_CONTINUE_PACKET];
for (int time = 0; time <= times; time++) {
/**
* Wait second before sending continue packet
*/
try {
Thread.sleep(200);
} catch (InterruptedException e) {
e.printStackTrace();
}
if (time == times) {
Log.i(TAG, "LAST PACKET ");
/**
* If you do not have enough characters to send continue packet,
* This is the last packet that will be sent to the band
*/
/**
* Packet length byte :
*/
/**
* Length of last packet
*/
int character_length = CHARACTERS.length()
- BLE.DEFAULT_BYTES_IN_CONTINUE_PACKET*times;
initial_packet[1] = Byte.valueOf(String.valueOf(character_length
+ BLE.INITIAL_MESSAGE_PACKET_LENGTH));
initial_packet[2] = BLE.SENDING_LAST_PACKET;
Log.i(TAG, "character_length " + character_length);
/**
* Message
*/
// Hex file
byte[] sending_last_hex = new byte[character_length];
// Hex file : Get next bytes
for (int i = 0; i < sending_last_hex.length; i++) {
sending_last_hex[i] =
CHARACTERS.getBytes()[sending_continue_hex.length*time + i];
}
// Merge byte[]
byte[] last_packet =
new byte[character_length + BLE.INITIAL_MESSAGE_PACKET_LENGTH];
System.arraycopy(initial_packet, 0, last_packet,
0, initial_packet.length);
System.arraycopy(sending_last_hex, 0, last_packet,
initial_packet.length, sending_last_hex.length);
// Set value for characteristic
characteristic.setValue(last_packet);
} else {
Log.i(TAG, "CONTINUE PACKET ");
/**
* If you have enough characters to send continue packet,
* This is the continue packet that will be sent to the band
*/
/**
* Packet length byte
*/
int character_length = sending_continue_hex.length;
/**
* TODO Default Length : 20 Bytes
*/
initial_packet[1] = Byte.valueOf(String.valueOf(
character_length + BLE.INITIAL_MESSAGE_PACKET_LENGTH));
/**
* If sent data length > 20 bytes (Default : BLE allow send 20 bytes one time)
* -> set 01 : continue sending next packet
* else or if after sent until data length < 20 bytes
* -> set 00 : last packet
*/
initial_packet[2] = BLE.SENDING_CONTINUE_PACKET;
/**
* Message
*/
// Hex file : Get first 17 bytes
for (int i = 0; i < sending_continue_hex.length; i++) {
Log.i(TAG, "Send stt : "
+ (sending_continue_hex.length*time + i));
// Get next bytes
sending_continue_hex[i] =
CHARACTERS.getBytes()[sending_continue_hex.length*time + i];
}
// Merge byte[]
byte[] sending_continue_packet =
new byte[character_length + BLE.INITIAL_MESSAGE_PACKET_LENGTH];
System.arraycopy(initial_packet, 0, sending_continue_packet,
0, initial_packet.length);
System.arraycopy(sending_continue_hex, 0, sending_continue_packet,
initial_packet.length, sending_continue_hex.length);
// Set value for characteristic
characteristic.setValue(sending_continue_packet);
}
// Write characteristic via BLE
mBluetoothGatt.writeCharacteristic(characteristic);
}
}
public boolean writeCharacteristic(BluetoothGattCharacteristic characteristic,
String data) {
if (mBluetoothAdapter == null || mBluetoothGatt == null) {
Log.w(TAG, "BluetoothAdapter not initialized");
return false;
}
if (ActivityBLEController.IS_FIRST_TIME) {
/**
* In the first time,
* should send the Title
*/
byte[] merge_title = sendTitle(data);
// Set value for characteristic
characteristic.setValue(merge_title);
// Write characteristic via BLE
mBluetoothGatt.writeCharacteristic(characteristic);
// Reset
ActivityBLEController.IS_FIRST_TIME = false;
return true;
} else {
/**
* In the second time,
* should send the Message
*/
if (data.length() <= BLE.LIMIT_CHARACTERS) {
sendMessage(characteristic, data);
// Reset
ActivityBLEController.IS_FIRST_TIME = true;
return true;
} else {
// Typed character
typed_character = data.length();
return false;
}
}
}
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