使用 ESP8266 进行通道更新和灯光控制
此示例演示如何更新通道并从 ThingSpeak™ TalkBack 队列中获取命令。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
ESP8266 和其他基于 ESP8266 的板卡
节点MCU
Wemos
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,替换
TALKBACK_ID
、YOUR_TALKBACK_API_KEY
、TALKBACK_COMMAND
和POSITION_NUMBER
。
POST https://api.thingspeak.com/talkbacks/TALKBACK_ID/commands api_key=YOUR_TALKBACK_API_KEY command_string=TALKBACK_COMMAND position=POSITION_NUMBER
对 ESP8266 进行编程
1) 下载最新的 Arduino® IDE。
2) 添加ESP8266板包。
3) 在“文件”下“> Preferences ,在“Additional Board Manager URLs”中输入 https://arduino.esp8266.com/stable/package_esp8266com_index.json 。
4) 选择Tools
> Boards
> Board Manager
。在搜索栏中输入 ESP8266
,然后选择并安装该软件包。
5) 在“Tools”菜单中,在 Arduino IDE 中选择适当的端口和板。用于生成此示例的硬件使用 Node MCU 1.0 (ESP 8266–12E)
选项。
6) 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。
7) 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: Writes values to fields 1,2,3, and 4 and checks a TalkBack queue every 20 seconds for new commands. The TalkBack documentation can be found at https://www.mathworks.com/help/thingspeak/talkback-app.html. Hardware: ESP8266-based boards Notes: - Requires ESP8266WiFi library and ESP8266 board add-on. See https://github.com/esp8266/Arduino for details. - Select the target hardware from Tools > Board Copyright 2018, The MathWorks, Inc. */ #include <ESP8266WiFi.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>; // Initialize values for ThingSpeak updates 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 Wi-Fi 网络的连接。从随机生成的数字创建 POST 消息。发送 POST、验证结果并检查 TalkBack 命令。然后在 20 秒内为下一个 POST请求生成新的随机数。
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; }