我有一個Raspberry Pi 3B和一個Pro(v2.0)MultiWii飛行控制器中的CRIUS All。我正在使用MultiWii 2.4版本和最新的NOOBS。我能夠設置好,現在我正試圖讓Raspberry Pi通過連接兩個主板的USB/Micro USB電纜與MultiWii進行通信。Raspberry Pi從MultiWii獲取數據
目前,MultiWii沒有返回任何數據,我不知道爲什麼。從我所看到的,我有正確的協議。我已經看了幾個工作代碼回購(用Arduino的Java編寫的Python代碼),並且遵循了MultiWii documentation並閱讀了關聯的forum post。
這是我寫的客戶端代碼。
package com.jmace.MaceDrone.msp;
import com.pi4j.io.serial.Baud;
import com.pi4j.io.serial.DataBits;
import com.pi4j.io.serial.FlowControl;
import com.pi4j.io.serial.Parity;
import com.pi4j.io.serial.Serial;
import com.pi4j.io.serial.SerialConfig;
import com.pi4j.io.serial.SerialDataEvent;
import com.pi4j.io.serial.SerialDataEventListener;
import com.pi4j.io.serial.SerialFactory;
import com.pi4j.io.serial.StopBits;
import java.io.IOException;
import java.math.BigInteger;
public class MultiWiiClient {
private final Serial serial;
//The preamble is defined by the protocol.
//Every message must begin with the characters $M
private static final String PREAMBLE = "$M";
//Character that denotes information being passed to the MultiWii
private static final char TO_MUTLIWII = '<';
//Character that denotes information being requested from by the MultiWii
private static final char FROM_MUTLIWII = '>';
public MultiWiiClient(String usbPort) {
SerialConfig config = new SerialConfig();
config.device(usbPort)
.baud(Baud._115200)
.dataBits(DataBits._8)
.parity(Parity.NONE)
.stopBits(StopBits._1)
.flowControl(FlowControl.NONE);
this.serial = SerialFactory.createInstance();
serial.addListener(new SerialDataEventListener() {
@Override
public void dataReceived(SerialDataEvent event) {
try {
System.out.println("[HEX DATA] " + event.getHexByteString());
System.out.println("[ASCII DATA] " + event.getAsciiString());
} catch (IOException e) {
e.printStackTrace();
}
}
});
try {
this.serial.open(config);
} catch (Exception e) {
e.printStackTrace();
}
}
public String sendRequest(MultiWiiRequest request) throws IllegalStateException, IOException {
String message = createMessage(request.getId(), false, null);
//////////////////////////////////////////////////////////////////////////////////
System.out.println(message);
System.out.println(String.format("%040x", new BigInteger(1, message.getBytes())));
//////////////////////////////////////////////////////////////////////////////////
return sendMessage(message);
}
public String sendCommand(MultiWiiCommand command, String payload) throws IllegalStateException, IOException {
String message = createMessage(command.getId(), true, payload);
return sendMessage(message);
}
/**
* This method creates the message that will be sent to the MultiWii
*
* Message format is as follows:
* +--------+---------+----+-------+----+---+
* |preamble|direction|size|command|data|crc|
* +--------+---------+----+-------+----+---+
*
* Preamble (2 bytes):
* Marks the start of a new message; always "$M"
*
* Direction (1 byte):
* Either '<' for a command going to the MultiWii or '>' for
* information being requested from the MultiWii
*
* Size (1 byte):
* The number of bytes in the payload
*
* Command (1 byte):
* The message ID of the command, as defined in the protocol
* 100's for requesting data, and 200's for requesting an action
*
* Data (variable bytes):
* The data to pass along with the command
*
* CRC (1 byte):
* Calculated with an XOR of the size, command, and each byte of data
*/
private String createMessage(int mutliWiiCommandnumber, boolean isCommand, String payload) {
StringBuilder message = new StringBuilder(PREAMBLE);
byte checksum=0;
//Get the direction of the message
if (isCommand) {
message.append(TO_MUTLIWII);
} else {
message.append(FROM_MUTLIWII);
}
int datalength = (payload != null) ? payload.length() : 0;
message.append((char) datalength);
checksum ^= datalength;
message.append((char) mutliWiiCommandnumber);
checksum ^= ((int) mutliWiiCommandnumber);
if (payload != null) {
for (char c : payload.toCharArray()){
message.append(c);
checksum ^= (int) c;
}
}
message.append((char) checksum);
return message.toString();
}
private String sendMessage(String message) throws IllegalStateException, IOException {
serial.write(message.getBytes());
serial.flush();
System.out.println("TESTING ------------------");
return "";
}
}
我使用「的/ dev/ttyUSB0」來連接,這是我證明是正確的位置,似乎當我運行其上工作(沒有錯誤,如果我開始運行,然後斷開USB它會拋出一個異常,因爲它失去了連接)。
在運行時,得到以下輸出(發送命令100,MSP_IDENT):
$M>dd
00000000000000000000000000244d3e006464
TESTING ------------------
更多代碼上下文參見my Git repo。
編輯:固定的校驗碼在我的崗位
你是對的。我結束了一段時間(serial.available()== 0)來等待數據回來,而不是。我添加了一個計數來確保我沒有等待太久的數據返回,否則我可以綁定線程。 – Jason