解码从arduino发送到用Python制作的TCP服务器的Byte数组

Question

我正在将传感器数据转换为字节，并将字节数组从arduino写入使用Python制作的TCP服务器，但不知何故，数组中的传感器数据在解码时触发UTF-8错误的变化。

UnicodeDecodeError: 'utf-8' codec can't decode byte 0xff in position 0: invalid start byte UnicodeDecodeError: 'utf-8' codec can't decode byte 0xcf in position 1: invalid continuation byte

"0xcf“和"0xff”从一个错误变为另一个错误。

我怀疑这是因为传感器数据有时可能是负值。我知道一个字节不能容纳一个负数，而UTF-8可以容纳0-256.我想我必须在负值之前发送一个专用的"-“符号。然而，我不能预测什么时候出现负值。因此，必须有更好的办法来做到这一点。我可以发送字节数组而不对其进行解码，但我怀疑这里也存在一些问题，因为前两个位置的值应该与其余6个位置的值不同，如下所示：b'\xff\x00\x00\x00\x00\x00\x00\x00' b'\x02\x00\x00\x00\x00\x00\x00\x00'

我的问题是:如何以字节的形式发送负值并对其进行正确解码。

对于上下文，我将附加我的代码。Arduino客户：`

#include <Ethernet.h>
#include <SPI.h>
#include "AK09918.h"
#include "ICM20600.h"
#include <Wire.h>
//----------------------------------

//tiltsensor
AK09918_err_type_t err;
int32_t x, y, z;
AK09918 ak09918;
ICM20600 icm20600(true);
int16_t acc_x, acc_y, acc_z;
int32_t offset_x, offset_y, offset_z;
double roll, pitch;
//----------------------------------

//Ethernet
byte mac[] = { 0xBE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED }; //not important if only one ethernet shield
byte ip[] = { 192, 168, X, X}; //IP of this arduino unit
byte server[] = { 192, 168, X, X}; //IP of server you want to contact
int tcp_port = 65432; // a nice port to send/acess the information on
EthernetClient client; 
//----------------------------------

//byte array
byte array[8] = {0, 0, 0, 0, 0, 0, 0, 0};
//----------------------------------

void setup()
{
  //tiltsensor
  Wire.begin();
  err = ak09918.initialize();
  icm20600.initialize();
  ak09918.switchMode(AK09918_POWER_DOWN);
  ak09918.switchMode(AK09918_CONTINUOUS_100HZ);
  Serial.begin(9600);
  err = ak09918.isDataReady();
  while (err != AK09918_ERR_OK) {
      Serial.println("Waiting Sensor");
      delay(100);
      err = ak09918.isDataReady();}
  Serial.println("Start figure-8 calibration after 2 seconds.");
  delay(2000);
  //calibrate(10000, &offset_x, &offset_y, &offset_z);
  Serial.println("");
  //----------------------------------

  //Ethernet
  Ethernet.begin(mac, ip);
  //Serial.begin(9600);
  delay(1000);
  Serial.println("Connecting...");
  if (client.connect(server, tcp_port)) { // Connection to server
    Serial.println("Connected to server.js");
    client.println();} 
  else {
    Serial.println("connection failed");}
  //----------------------------------
}

void loop()
{
  //tiltsensor
  acc_x = icm20600.getAccelerationX();
  acc_y = icm20600.getAccelerationY();
  acc_z = icm20600.getAccelerationZ();
  roll = atan2((float)acc_y, (float)acc_z) * 57.3;
  pitch = atan2(-(float)acc_x, sqrt((float)acc_y * acc_y + (float)acc_z * acc_z)) * 57.3;
  //----------------------------------

  //bytearray
  array[0] = byte(roll);
  array[1] = byte(pitch);
  //----------------------------------

  //test
  Serial.write(array, 8);
  Serial.println();
  delay(500); 
  //----------------------------------


  //Ethernet
  if (client.available()) {
      //client.print(array);
      //client.write(array[0]);
      client.write(array, 8);
      //client.write(array, 8);//((uint8_t*) array, sizeof(array));
      delay(3000); 
    }
  if (!client.connected()) {
    Serial.println();
    Serial.println("disconnecting.");
    client.stop();
    for(;;)
      ;
  }
  //----------------------------------
}

`

TCP服务器(python)：

`

# echo-server.py
import time
import socket

HOST = "192.168.X.X"  # Standard loopback interface address (localhost)
PORT = 65432  # Port to listen on (non-privileged ports are > 1023)

with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
    s.bind((HOST, PORT))
    s.listen()
    conn, addr = s.accept()
    with conn:
        print(f"Connected by {addr}")
        while True:
            data = conn.recv(1024)
            #msg = s.recv(1024)
            #print(msg.decode("utf-8"))
            print(data.decode("utf-8"))
            #time.sleep(3)
            #conn.sendall(data)
            if not data:
                break
            conn.send(data)

`

我能够建立到服务器的连接，客户端可以给它写信。但是，我会得到UnicodeDecodeError: 'utf-8' codec can't decode byte 0xa4 in position 0: invalid start byte类型错误。

Answer 1

我取得了一些进展，

对于Arduino：

#include <Ethernet.h>
#include <SPI.h>
#include "AK09918.h"
#include "ICM20600.h"
#include <Wire.h>
//----------------------------------

//tiltsensor
AK09918_err_type_t err;
int32_t x, y, z;
AK09918 ak09918;
ICM20600 icm20600(true);
int16_t acc_x, acc_y, acc_z;
int32_t offset_x, offset_y, offset_z;
double roll, pitch;
//----------------------------------

//Ethernet
byte mac[] = { 0xBE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED }; //not important if only one ethernet shield
byte ip[] = { 192, 168, X, XX}; //IP of this arduino unit
byte server[] = { 192, 168, X, XX}; //IP of server you want to contact
int tcp_port = 65432; // a nice port to send/acess the information on
EthernetClient client; 
//----------------------------------


//byte array
union some_data{  //convert a float to 4 bytes
  float tobytes;
  byte bytearray[4];
};

byte array[14] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0}; //intial array
//----------------------------------

void setup()
{
  //tiltsensor
  Wire.begin();
  err = ak09918.initialize();
  icm20600.initialize();
  ak09918.switchMode(AK09918_POWER_DOWN);
  ak09918.switchMode(AK09918_CONTINUOUS_100HZ);
  Serial.begin(9600);
  err = ak09918.isDataReady();
  while (err != AK09918_ERR_OK) {
      Serial.println("Waiting Sensor");
      delay(100);
      err = ak09918.isDataReady();}
  Serial.println("Start figure-8 calibration after 2 seconds.");
  delay(2000);
  //calibrate(10000, &offset_x, &offset_y, &offset_z);
  Serial.println("");
  //----------------------------------

  //Ethernet
  Ethernet.begin(mac, ip);
  //Serial.begin(9600);
  delay(1000);
  Serial.println("Connecting...");
  if (client.connect(server, tcp_port)) { // Connection to server
    Serial.println("Connected to server.js");
    client.println();} 
  else {
    Serial.println("connection failed");}
  //----------------------------------

  //byte array

  //----------------------------------
}

void loop()
{
  //tiltsensor
  acc_x = icm20600.getAccelerationX();
  acc_y = icm20600.getAccelerationY();
  acc_z = icm20600.getAccelerationZ();
  roll = atan2((float)acc_y, (float)acc_z) * 57.3;
  pitch = atan2(-(float)acc_x, sqrt((float)acc_y * acc_y + (float)acc_z * acc_z)) * 57.3;
  //----------------------------------


  //bytearray
   if (roll < 0) {array[0] = 0;}  //put identifier for positive or negative value in specific posision in byte array
  else {array[0] = 1;}

  if (pitch < 0) {array[5] = 0;} // same for second sensor value
  else {array[5] = 1;}

  union some_data sensor1;  //use the union function separately
  union some_data sensor2;

  sensor1.tobytes =abs(roll); //get byte array for sensor value
  sensor2.tobytes =abs(pitch); //get byte array for sensor value

  for (int i=0; i<sizeof sensor1.bytearray/sizeof sensor1.bytearray[0]; i++) {   //put sensor value byte array into main byte array
    array[1+i] =  sensor1.bytearray[i];
    array[6+i] =  sensor2.bytearray[i];
    }
  //----------------------------------

  //test
  Serial.write(array, sizeof array);
  Serial.println();
  delay(500); 
  //----------------------------------


  //Ethernet
  if (client.available()) {
      //client.print(array);
      //client.write(array[0]);
      client.write(array, sizeof array);
      //client.write(array, 8);//((uint8_t*) array, sizeof(array));
      delay(3000); 
    }
  if (!client.connected()) {
    Serial.println();
    Serial.println("disconnecting.");
    client.stop();
    for(;;)
      ;
  }
  //----------------------------------
}

对于python。

# echo-server.py
import time
import socket

HOST = "192.168.XX.XX"  # Standard loopback interface address (localhost)
PORT = 65432  # Port to listen on (non-privileged ports are > 1023)

with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
    s.bind((HOST, PORT))
    s.listen()
    conn, addr = s.accept()
    with conn:
        print(f"Connected by {addr}")
        while True:
            data = conn.recv(1024)
            #msg = s.recv(1024)
            #print(msg.decode("utf-8"))
            print(data)#.decode("utf-8"))
            #time.sleep(3)
            #conn.sendall(data)
            if not data:
                break
            conn.send(data)

Answer 2

正如评论中提到的@hcheung，在Arduino方面，您可以简单地使用

Serial.write(&roll, 4);
Serial.wirte(&pitch,4);

符号已经以这些字节作为第一位进行编码。例如，请参见维基。

在您的python方面，我建议您查看一下模块

对于您的具体情况，只需使用

roll, pitch = struct.unpack("dd", data)

其中"dd"描述了两种d的格式。