ESP8266 NodeMCU 无法发送 TCP 命令 - 相同的代码适用于 Arduino Uno？

Question

我是这方面的菜鸟，所以希望是一个愚蠢的显而易见的人。

我正在尝试创建一个简单的温度/湿度传感器，它从 DHT22 获取读数并使用 ESP8266 将它们 ping 到 Thingspeak 的 API，然后绘制/存储等。

我在下面粘贴了代码 - 它适用于 Arduino Uno，我正在尝试将其缩小到 ESP8266 上，这样我就可以在房子周围生产许多小型温度传感器。

症状

• wifi 连接正常
• 它正在生成正确的 API 字符串（我已经通过手动剪切并将其粘贴到浏览器中进行了测试）
• 温度传感器也生成正确的读数
• 它返回“数据失败！”在串行监视器中，表明这是代码中发生错误的位置

我不知道从 Arduino Uno 迁移到 ESP8266 是否有什么奇怪的地方会导致问题（即需要不同的库，TCP 命令不同等）

非常感谢经验丰富的老手的任何帮助！

这是串行监视器输出的 sn-p 和代码（只是密码/api 等）

22:16:50.266 -> **************
22:16:57.579 -> Wifi Connection Successful
22:16:57.579 -> The IP Address of the Sensor is:192.168.1.211
22:16:57.579 -> Humidity: 41.50
22:16:57.579 -> Temperature: 21.70
22:16:57.579 -> AT+CIPSTART="TCP","api.thingspeak.com",80
22:17:00.574 -> AT+CIPSEND=63
22:17:01.561 -> AT+CIPCLOSE
22:17:02.577 -> Data Fail!
22:17:02.577 -> GET /update?apikey=<REMOVED>&field1=21.70&field2=41.50

#include<stdlib.h>
#include "DHT.h"
#include <ESP8266WiFi.h>

#define SSID "<REMOVED>" //your network name
#define PASS "<REMOVED>" //your network password
#define API "<REMOVED>" //api string
#define IP "api.thingspeak.com" // thingspeak.com
#define DHTPIN 4     // what pin the DHT sensor is connected to
#define DHTTYPE DHT22   // Change to DHT22 if that's what you have
#define Baud_Rate 115200 //Another common value is 9600
#define DELAY_TIME 300000 //time in ms between posting data to ThingSpeak

//Can use a post also
String GET = String("GET /update?apikey=") + API + "&field1=";
String FIELD2 = "&field2=";

//if you want to add more fields this is how
//String FIELD3 = "&field3=";

bool updated;

DHT dht(DHTPIN, DHTTYPE);

//this runs once
void setup()
{
  delay(5000);
  Serial.begin(Baud_Rate);
  // Connect to WIFI
  WiFi.begin(SSID, PASS);
  while (WiFi.status() != WL_CONNECTED)
  {
    delay(500);
    Serial.print("*");
  }

  Serial.println("");
  Serial.println("Wifi Connection Successful");
  Serial.print("The IP Address of the Sensor is:");
  Serial.println(WiFi.localIP()); //Print the IP Address


  //initalize DHT sensor
  dht.begin();
}

//this runs over and over
void loop() {
  float h = dht.readHumidity();
  Serial.print("Humidity: ");
  Serial.println(h);
  // Read temperature as Fahrenheit (isFahrenheit = true)
  float c = dht.readTemperature();
  Serial.print("Temperature: ");
  Serial.println(c);

  // Check if any reads failed and exit early (to try again).
  if (isnan(h) || isnan(c)) {
    Serial.println("Reading DHT22 Failed, exiting");
    return;
  }

  //update ThingSpeak channel with new values
  updated = updateTemp(String(c), String(h));

   //wait for delay time before attempting to post again
  delay(DELAY_TIME);
}

bool updateTemp(String tempC, String humid) {
  //initialize your AT command string
  String cmd = "AT+CIPSTART=\"TCP\",\"";

  //add IP address and port
  cmd += IP;
  cmd += "\",80";

  //connect
  Serial.println(cmd);
  delay(2000);
  if (Serial.find("Error")) {
    return false;
  }

  //build GET command, ThingSpeak takes Post or Get commands for updates, I use a Get
  cmd = GET;
  cmd += tempC;
  cmd += FIELD2;
  cmd += humid;
  cmd += "\r\n";  

  //continue to add data here if you have more fields such as a light sensor
  //cmd += FIELD3;
  //cmd += <field 3 value>

  //Serial.println(cmd);
  //Use AT commands to send data
  Serial.print("AT+CIPSEND=");
  Serial.println(cmd.length());
  if (Serial.find(">")) {
    //send through command to update values
    Serial.print(cmd);
  } else {
    Serial.println("AT+CIPCLOSE");
  }

  if (Serial.find("OK")) {
    //success! Your most recent values should be online.
    Serial.println("Data Sent!");
    return true;
  } else {
    Serial.println("Data Fail!");
    Serial.println(cmd);
    return false;
  }
}

boolean connectWiFi() {
  //set ESP8266 mode with AT commands
  Serial.println("AT+CWMODE=1");
  delay(2000);

  //build connection command
  String cmd = "AT+CWJAP=\"";
  cmd += SSID;
  cmd += "\",\"";
  cmd += PASS;
  cmd += "\"";

  //connect to WiFi network and wait 5 seconds
  Serial.println(cmd);
  delay(5000);

  //if connected return true, else false
  if (Serial.find("OK")) {
    Serial.println("WIFI connected");
    return true;
  } else {
    Serial.println("WIFI not connected");
    return false;
  }
}

Answer 1

首先在我们讨论您面临的问题之前，您需要了解使用 ESP8266 的两种不同方式：

• 将其用作 WiFi 调制解调器；
• 将其用作独立的 MCU。

当将它用作 WiFi 调制解调器时，您使用 AT-command 与它通信，默认情况下，大多数 ESP8266 模块都是这样做的，它带有 At-command 固件。

当您使用 ESP8266 作为 MCU 时，您使用 Arduino 草图刷新 ESP8266，它会覆盖 AT-Command 固件并使用 Arduino 引导加载程序上传，并允许 ESP8266 像 Arduino 一样用作独立 MCU .

您提到在使用 Arduino Uno 时可以毫无问题地与 ESP8266 通信，这表明您正在使用 AT 命令与 ESP8266 通信（并且您的部分代码表明是这种情况）。

当您将 Arduino 草图上传到 ESP8266 以将其用作独立 MCU 时，您需要使用 Arduino 库（例如 ESP8266WiFi）与 ESP8266 通信，该库将负责与 ESP8266 芯片的较低级别通信。这就是为什么你可以使用ESP8266WiFi类提供的能力来建立WiFi。

但是，updateTemp() 中的代码仍在使用不再起作用的 AT 命令。您将需要使用ESP8266WebClient 或ESP8266HTTPClient（这个更简单、更容易）库来建立http 连接。这是我为使用ESP8266HTTClient 库处理HTTP 请求而修改的代码。顺便说一句，编译好的代码，但我没有用 thinkspeak 服务器测试它，因为我不使用 thinkspeak，也没有 api-key。

#include <DHT.h>
#include <ESP8266WiFi.h>
#include <ESP8266HTTPClient.h>

#define SSID "<REMOVED>" //your network name
#define PASS "<REMOVED>" //your network password
#define API "<REMOVED>" //api string
#define IP "api.thingspeak.com" // thingspeak.com
#define PORT 80
#define DHTPIN 4     // what pin the DHT sensor is connected to
#define DHTTYPE DHT22   // Change to DHT22 if that's what you have
#define BAUD_RATE 115200 //Another common value is 9600
#define DELAY_TIME 300000 //time in ms between posting data to ThingSpeak

DHT dht(DHTPIN, DHTTYPE);

//this runs once
void setup()
{
  Serial.begin(BAUD_RATE);

  // Connect to WIFI
  WiFi.begin(SSID, PASS);
  while (WiFi.status() != WL_CONNECTED)
  {
    delay(500);
    Serial.print("*");
  }
  Serial.println("");
  Serial.println("Wifi Connection Successful");
  Serial.print("The IP Address of the Sensor is:");
  Serial.println(WiFi.localIP());

  //initalize DHT sensor
  dht.begin();
}

//this runs over and over
void loop() {
  float h = dht.readHumidity();
  Serial.print("Humidity: ");
  Serial.println(h);
  // Read temperature as Fahrenheit (isFahrenheit = true)
  float c = dht.readTemperature();
  Serial.print("Temperature: ");
  Serial.println(c);

  // Check if any reads failed and exit early (to try again).
  if (isnan(h) || isnan(c)) {
    Serial.println("Reading DHT22 Failed, exiting");
    return;
  }

  //update ThingSpeak channel with new values
  updateTemp(c, h);

  //wait for delay time before attempting to post again
  delay(DELAY_TIME);
}


bool updateTemp(float tempC, float humid) {

  WiFiClient client;    // Create a WiFiClient to for TCP connection

  if (!client.connect(IP, PORT)) {
   Serial.println("HTTP connection failed");
   return false;
  }

  Serial.println("Sending data to server");
  if (client.connected()) {
    client.print("GET /update?api_key="); client.print(API);
    client.print("&field1="); client.print(String(tempC));
    client.print("&field2="); client.print(String(humid));
    client.println(" HTTP/1.1");
    client.print("Host: "); client.println(IP);
    client.println("Connection: close");
    client.println();    //extra "\r\n" as per HTTP protocol
  }

  // wait for data to be available
  unsigned long timeout = millis();
  while (client.available() == 0) {
    if (millis() - timeout > 5000) {
     Serial.println("HTTP Client Timeout !");
     client.stop();
     return false;
    }
  }

  Serial.println("Receiving HTTP response");
  while (client.available()) {
   char ch = static_cast<char>(client.read());
   Serial.print(ch);
  }
  Serial.println();

  Serial.println("Closing TCP connection");
  client.stop();
  return true;
}

Answer 2

您必须解决三个问题：
摆脱 delay() 并不是说​​您不应该不时调用例程来不锤击您的服务器。原因：delay() 函数在指定的时间内停止 CPU。
在设置中可以等待一些硬件初始化，并可以快速测试/调试简单的例程。服务器/客户端场景中的坏主意（通信任务与用户任务并行运行）并且在例如带有 2 个 CPU 的 ESP32。一个简短的如何为您的程序。

unsigned long previousMillis = 0; 

setup() {
 ....
} 

loop(){
  if (millis() - previousMillis > DELAY_TIME) {   // we check for elapsed time

   // What ever needs to be done all DELAY_TIME ms  

   previousMillis  = millis(); // we "reset" the timer
   }
// other code which needs no delayed execution
}

同时更改 Arduino 的代码并将其提升到一个新的水平-
第二点：去掉String类，改用固定字符。
原因是String类的内存管理不好，破坏了你的堆，导致ESP迟早崩溃，chars编译为flash，没有这个问题.如何使用您的命令/功能之一的简短示例：

// instead of #define API "<REMOVED>" //api String use
const char* API = "<REMOVED>" // pointer to the char API

//Can use a post also
char fixPartGET[128] = '\0';  // takes 255 chars and the terminator, if needed enlarge
char cmd[256] = '\0';  // takes 127 chars and the terminator, if needed enlarge
char numBuffer [16] = '\0'; // we use for float conversions
strcpy (fixPartGET, "GET /update?apikey="); // Copy empties
strcat (fixPartGET, API);
strcat (fixPartGET, "&field1=");
const char* FIELD2 = "&field2=";

setup(){
    ....
}

loop(){
    ....
}

bool updateTemp( float c, float h) {

  if (WiFi.status() != WL_CONNECTED) {
    return false;
  }

  //build GET command, ThingSpeak takes Post or Get commands for updates, I use a Get
  strcpy(cmd, fixPartGET); // start building the GET command
  // The dtostrf() function converts the double value passed in into an ASCII representation
  dtostrf(c, 6, 2, numBuffer); // change to what you need as precision
  strcat(cmd, numBuffer);
  strcat(cmd, FIELD2);
  dtostrf(h, 6, 2, numBuffer); // change to what you need as precision
  strcat(cmd, numBuffer);
  strcat(cmd, "\r\n");  

  //continue to add data here if you have more fields such as a light sensor
  //strcat(cmd, FIELD3);

  //Some other code to discuss
return true;
}

最后一点
与 AP 的 WiFi 通信 - 查看 WiFi 库的示例并使用串行 AT 命令解决麻烦。目前，这些命令通过 USB 电缆而不是 WiFi 运行。与 Arduino 相比，nodeMCU 是一台功能强大的机器，但由于技术概念，它更容易出现不稳定。 我提出的更改 1 和 2 可以而且应该在 Arduino 上实现，作为第一次习惯这种方法。如果运行此程序，请在 NodeMCU 上将 AT 更改为 WiFi 客户端功能。 ESP8266WiFi.h 库示例 WiFiClientBasic 和 WiFiClient 可能有助于快速获得结果（查找 client.print(...) ）。