Arduino 上的通道更新和灯光控制
此示例展示如何更新通道并从 ThingSpeak™ TalkBack 队列获取命令。使用命令更改板载 LED 的状态。
当您的应用涉及您只想在队列中有命令时运行的计算机时,请使用 TalkBack。
您可以同时更新通道并检索保存在 TalkBack 队列中的最新命令。将参数 talkback_key
添加到 POST请求中,ThingSpeak 将在响应中返回最新的 TalkBack 命令。
支持的硬件
Arduino Uno 或类似的带 Wi-Fi 扩展板的 Arduino 板
MKR1000
先决条件
您必须至少设置一个通道才能完成此示例。创建一个Channel,如Collect Data in a New Channel所示,并记录写入API密钥。您还需要设置 TalkBack。转到 App > “TalkBacks”并选择“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 Web 界面将命令添加到 TalkBack 队列。您可以将 TalkBack 配置为最多 8000 个命令。
使用 ThingSpeak API。您可以使用 HTTP POST请求将命令添加到队列中。在以下 POST 中,将
TALKBACK_ID
、YOUR_TALKBACK_API_KEY
、TALKBACK_COMMAND
和POSITION_NUMBER
替换为适当的值来自您通道的价值。
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) 将 WiFi101
添加到“库管理器”(如果尚不存在)。
a) 选择 Sketch > Include Library > Manage Libraries 。
b) 选择“WiFi101”库并点击“安装”。
3) 将 SPI
添加到“库管理器”(如果尚不存在)。
a) 选择 Sketch > Include Library > Manage Libraries 。搜索 SPI
。
b) 选择 SPI
将其添加到代码中。
4) 在“Tools”菜单中,在 Arduino IDE 中选择适当的端口和板。
5) 将代码粘贴到Arduino IDE中。添加您的 Wi-Fi 网络信息、TalkBack API 密钥和 TalkBack 号码。
6) 对设备进行编程,然后观察串行监视器和 LED,以观察命令消耗时的变化。每个执行的命令都会从列表中删除。您需要在使用更多命令后将它们添加到列表中。
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 ID 和 API 密钥的通道号和 TalkBack 参数。
/* 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并启动串行监视器。
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。然后为 20 秒内的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; }