问题描述
我有一个针对Arduino Nano和NodeMCU ESP8266的代码。两者都可以正常工作并提供输出,但是输出不是我想要的。
从数据库获取数据并将其发送到Arduino的NodeMCU代码:
#include <ESP8266WiFi.h>
#include <WiFiClient.h>
#include <ESP8266WebServer.h>
#include <ESP8266HTTPClient.h>
#include <SoftwareSerial.h>
#include <ArduinoJson.h>
SoftwareSerial s(D6,D5);
int Led_OnBoard = 2; // Initialize the Led_OnBoard
const char* ssid = "ssid"; // Your wifi Name
const char* password = "password"; // Your wifi Password
const char *host = "pc/server IP"; //Your pc or server (database) IP,example : 192.168.0.0,if you are a windows os user,open cmd,then type ipconfig then look at IPv4 Address.
void setup() {
delay(1000);
pinMode(Led_OnBoard,OUTPUT); // Initialize the Led_OnBoard pin as an output
Serial.begin(115200);
WiFi.mode(WIFI_OFF); //Prevents reconnection issue (taking too long to connect)
delay(1000);
WiFi.mode(WIFI_STA); //This line hides the viewing of ESP as wifi hotspot
WiFi.begin(ssid,password); //Connect to your WiFi router
Serial.println("");
Serial.print("Connecting");
// Wait for connection
while (WiFi.status() != WL_CONNECTED) {
digitalWrite(Led_OnBoard,LOW);
delay(250);
Serial.print(".");
digitalWrite(Led_OnBoard,HIGH);
delay(250);
}
digitalWrite(Led_OnBoard,HIGH);
//If connection successful show IP address in serial monitor
Serial.println("");
Serial.println("Connected to Network/SSID");
Serial.print("IP address: ");
Serial.println(WiFi.localIP()); //IP address assigned to your ESP
s.begin(115200);
}
void loop() {
HTTPClient http; //Declare object of class HTTPClient
http.begin("http://pc/server IP/Nodemcu_db_record_view/GetValue.php");
http.addHeader("Content-Type","application/x-www-form-urlencoded");
int httpCode = http.GET(); //Get the request
String payload = http.getString(); //Get the response payload
Serial.println(httpCode); //Print HTTP return code
Serial.println(payload);
http.end(); //Close connection
StaticJsonBuffer<1000> jsonBuffer;
JsonObject& root = jsonBuffer.createObject();
root["data1"] = payload;
if (s.available() >= 0)
{
root.printTo(s);
}
}
正在从NodeMCU接收数据的Arduino代码:
#include <SoftwareSerial.h>
SoftwareSerial s(5,6);
#include <ArduinoJson.h>
void setup() {
// Initialize Serial port
Serial.begin(115200);
s.begin(115200);
while (!Serial) continue;
}
void loop() {
StaticJsonBuffer<1000> jsonBuffer;
JsonObject& root = jsonBuffer.parseObject(s);
if (root == JsonObject::invalid())
return;
int data1=root["data1"];
Serial.println(data1);
}
用于从NodeMCU调用数据库时查询数据库的PHP代码:
<?php
$server="localhost";
$username="root";//THE DEFAULT USERNAME OF THE DATABASE
$password="";
$dbname="automation";
$con=mysqli_connect($server,$username,$password,$dbname) or die("unable to connect");
$sql="SELECT ButtonState FROM project WHERE Date = '2020-10-14'";
$result=mysqli_query($con,$sql);
if ($result->num_rows > 0) {
while($row = $result->fetch_assoc()) {
echo $row["ButtonState"];
}
}
?>
以上是我编写的全部内容,并且可以正常工作。它不断输出,但我只希望串行监视器上有1个值。
感谢您的帮助,因为我是Arduino世界的新手。 我尝试搜索过多,但无法解决此问题。
修改 另一个问题是,当数据库列中的数据为1时,串行监视器上的输出有时会更改,但是如果数据库列中的数据为0,则它保持不变。查看图片中的输出。
解决方法
问题是您在loop
函数中的代码是repeated incessantly
。因此,您必须add a variable on the top of your program
并在执行代码时将其设置为true。
尝试以下代码示例:
// add a variable on the top
bool printed = false;
void loop() {
// only execute if the variable is false
if (printed == false) {
StaticJsonBuffer<1000> jsonBuffer;
JsonObject& root = jsonBuffer.parseObject(s);
if (root == JsonObject::invalid())
return;
int data1 = root["data1"];
Serial.println(data1);
// set the variable to true so that it is not executed twice
printed = true;
}
}