Arduino 上的通道更新和灯光控制

打开实时脚本

此示例显示如何更新您的通道并从 ThingSpeak™ TalkBack 队列中获取命令。使用命令来改变板载 LED 的状态。

当您的应用程序涉及仅当队列中有命令时才想要运行的计算机时，请使用 TalkBack。

您可以同时更新您的通道并检索保存在 TalkBack 队列中的最新命令。在您的 POST 请求中添加参数 talkback_key，ThingSpeak 将在响应中返回最新的 TalkBack 命令。

支持的硬件

Arduino Uno 或类似带 Wi-Fi Shield 的 Arduino 开发板
MKR1000

前提条件

您必须至少设置一个通道才能完成此示例。按照在新通道中收集数据所示创建一个通道，并记录写入 API Key。您还需要设置 TalkBack。转至 Apps > TalkBacks，然后选择 New TalkBack。

将命令添加到 TalkBack 队列

您可以通过以下两种方式之一将命令添加到 TalkBack 队列。

使用 ThingSpeak TalkBack 网络界面将命令添加到 TalkBack 队列。您可以将 TalkBack 配置为最多 8000 条命令。
使用 ThingSpeak API。您可以使用 HTTP POST 请求将命令添加到队列。在以下 POST 中，将 TALKBACK_ID、YOUR_TALKBACK_API_KEY、TALKBACK_COMMAND 和 POSITION_NUMBER 替换为您通道中的相应值。

POST https://api.thingspeak.com/talkbacks/TALKBACK_ID/commands
 api_key=YOUR_TALKBACK_API_KEY
     command_string=TALKBACK_COMMAND
     position=POSITION_NUMBER

对您的设备进行编程

1) 下载最新的 Arduino®IDE。

2) 如果 WiFi101 尚未添加到 Library Manager 中。

a) 选择 Sketch > Include Library > Manage Libraries。

b) 选择 WiFi101 库并点击 Install。

3) 如果 SPI 尚未添加到 Library Manager 中。

a) 选择 Sketch > Include Library > Manage Libraries。搜索 SPI。

b) 选择 SPI 将其添加到您的草图中。

4) 在 Tools 菜单中，选择 Arduino IDE 中适当的端口和主板。

5) 将代码粘贴到 Arduino IDE。添加您的 Wi-Fi 网络信息、您的 TalkBack API 密钥和您的 TalkBack 号码。

6) 对设备进行编程，然后观察串行监视器和 LED，以观察命令使用时的变化。每个执行的命令都会从列表中删除。使用完命令后，您需要将更多命令添加到列表中。

代码

1)首先包含适当的库并定义变量。输入您的网络 SSID 和密码。编辑通道号码和 TalkBack 参数（ID 和 API 密钥）。

/*
WriteMultipleFieldsAndFetchCommandFromTalkBack

Description: Checks a TalkBack queue every 60 seconds and sets the state of the built-in LED according
             to the latest command fetched. Turn the LED on and off by using the commands TURN_ON and TURN_OFF.
             The TalkBack documentation can be found at https://www.mathworks.com/help/thingspeak/talkback-app.html.
             
           
Hardware: Arduino Wi-Fi Shield 101

Notes:
- Requires WiFi101 library. Use the WiFi101 library version 0.13.0 or older. WiFi101 library versions 0.14.0 and newer have a bug
  that prevents this ThingSpeak library from working properly.
- Make sure the WiFi Shield 101 has updated firmware. Find instructions at https://www.arduino.cc/en/Tutorial/FirmwareUpdater.

Copyright 2018, The MathWorks, Inc.
*/

#include "ThingSpeak.h"
#include <SPI.h>
#include <WiFi101.h>

char ssid[] = <enter your SSID>;   // your network SSID (name) 
char pass[] = <enter your password>;   // your network password

WiFiClient  client;

unsigned long myChannelNumber = <enter your channel ID>;
unsigned long myTalkBackID = <enter your TalkBack ID>;
const char * myTalkBackKey = <enter your TalkBack API key>;

// Some values to send to ThingSpeak
int number1 = 0;
int number2 = random(0,100);
int number3 = random(0,100);
int number4 = random(0,100);

2) 在 setup 函数中，初始化 LED 并启动串口监视器。

void setup() {
  pinMode(LED_BUILTIN, OUTPUT);  // Set up LED
  Serial.begin(115200);  // Initialize serial
}

3) 在主循环中，首先建立与本地无线网络的连接。从随机生成的数字创建 POST 消息。发送 POST 请求，验证结果并检查 TalkBack 命令。然后在 20 秒内为下一次通道更新生成新的随机数。

void loop() {

  // Connect or reconnect to Wi-Fi
  if(WiFi.status() != WL_CONNECTED){
    Serial.print("Attempting to connect to SSID: ");
    Serial.println(String(ssid);
    while(WiFi.status() != WL_CONNECTED){
      WiFi.begin(ssid, pass);  
      Serial.print(".");
      delay(5000);     
    } 
    Serial.println("\nConnected.");
  }

  // Create the message body for the POST out of the values
  String postMessage =  String("field1=") + String(number1) +
                        String("&field2=") + String(number2) +
                        String("&field3=") + String(number3) +
                        String("&field4=") + String(number4) +
                        String("&api_key=") + String(myWriteAPIKey) +
                        String("&talkback_key=") + String(myTalkBackKey);                      
                       

   // Make a string for any commands in the queue
  String newCommand = String();

  // Make the POST to ThingSpeak
  int x = httpPOST(postMessage, newCommand);
  client.stop();
  
  // Check the result
  if(x == 200){
    Serial.println("checking queue..."); 
    // check for a command returned from TalkBack
    if(newCommand.length() != 0){

      Serial.print("  Latest command from queue: ");
      Serial.println(newCommand);
      
      if(newCommand == "TURN_ON"){
        digitalWrite(LED_BUILTIN, HIGH);  
      }

      if(newCommand == "TURN_OFF"){
        digitalWrite(LED_BUILTIN, LOW);
      }
    }
    else{
      Serial.println("  Nothing new.");  
    }
    
  }
  else{
    Serial.println("Problem checking queue. HTTP error code " + String(x));
  }

  // Confirm code works by changing values
  number1++;
  if(number1 > 99){
    number1 = 0;
  }
  number2 = random(0,100);
  number3 = random(0,100);
  number4 = random(0,100);
  
  delay(20000); // Wait 20 seconds to update the channel again
}

4) 使用 httpPOST 函数将数据发布到 ThingSpeak 并读取下一个 TalkBack 命令。

// General function to POST to ThingSpeak
int httpPOST(String postMessage, String &response){

  bool connectSuccess = false;
  connectSuccess = client.connect("api.thingspeak.com",80);

  if(!connectSuccess){
      return -301;   
  }
  
  postMessage += "&headers=false";
  
  String Headers =  String("POST /update HTTP/1.1\r\n") +
                    String("Host: api.thingspeak.com\r\n") +
                    String("Content-Type: application/x-www-form-urlencoded\r\n") +
                    String("Connection: close\r\n") +
                    String("Content-Length: ") + String(postMessage.length()) +
                    String("\r\n\r\n");

  client.print(Headers);
  client.print(postMessage);

  long startWaitForResponseAt = millis();
  while(client.available() == 0 && millis() - startWaitForResponseAt < 5000){
      delay(100);
  }

  if(client.available() == 0){       
    return -304; // Didn't get server response in time
  }

  if(!client.find(const_cast<char *>("HTTP/1.1"))){
      return -303; // Couldn't parse response (didn't find HTTP/1.1)
  }
  
  int status = client.parseInt();
  if(status != 200){
    return status;
  }

  if(!client.find(const_cast<char *>("\n\r\n"))){
    return -303;
  }

  String tempString = String(client.readString());
  response = tempString;
  
  return status;
    
}