求指点
/********************************************************* PID RelayOutput Example
* Same as basic example, except that this time, the output
* is going to a digital pin which (we presume) is controlling
* a relay.the pid is designed to Output an analog value,
* but the relay can only be On/Off.
*
* to connect them together we use "time proportioning
* control"it's essentially a really slow version of PWM.
* first we decide on a window size (5000mS say.) we then
* set the pid to adjust its output between 0 and that window
* size.lastly, we add some logic that translates the PID
* output into "Relay On Time" with the remainder of the
* window being "Relay Off Time"
PID继电器输出范例
与基本范例相同，这一次输出是一个数字引脚控制的继电器。PID被设计成
输出一个模拟值，但是继电器只有开关状态。
为了联系上两者，我们使用时间比例控制，它本质上是一个很慢的PWM。
首先我们决定一个窗口时间（比如5000ms）。
然后设置PID适应它的输出在0到窗口时间的范围。
最后我们添加一些逻辑，把PID输出转换成“继电器接通时间”和剩余的
“继电器断开时间”
********************************************************/
#include <PID_v1.h>
#define RelayPin 8
// 定义我们将要使用的变量
//Define Variables we'll be connecting to
double Setpoint, Input, Output;
//指定链接和最初的调优参数
//Specify the links and initial tuning parameters
PID myPID(&Input, &Output, &Setpoint,2,5,1, DIRECT);
int WindowSize = 2000;
unsigned long windowStartTime;
void setup()
{
windowStartTime = millis();
//初始化变量
//initialize the variables we're linked to
Setpoint = 100; //??????????????????????????????????????(是不是设定温度值）
//告诉PID在从0到窗口大小的范围内取值
//tell the PID to range between 0 and the full window size
myPID.SetOutputLimits(0, WindowSize);
//开启PID
//turn the PID on
myPID.SetMode(AUTOMATIC);
}
void loop()
{
Input = analogRead(0);
myPID.Compute();
/************************************************
* turn the output pin on/off based on pid output 基于PID输出，打开或关闭端口输出
************************************************/
if(millis() - windowStartTime>WindowSize)
{ //time to shift the Relay Window 继电器窗口时间
windowStartTime += WindowSize;
}
if(Output < millis() - windowStartTime) digitalWrite(RelayPin,HIGH);
else digitalWrite(RelayPin,LOW);
}
这是网上的pid控制代码，其中红字部分为读取温度传感器，因为它只需要控制100度。所以用的是lm35之类的传感器。
我需要控制的300度，所以用max6675加k型热电偶
#include "max6675.h"
int thermoDO = 4;
int thermoCS = 5;
int thermoCLK = 6;
MAX6675 thermocouple(thermoCLK, thermoCS, thermoDO);
int vccPin = 3;
int gndPin = 2;
void setup() {
Serial.begin(9600);
// use Arduino pins
pinMode(vccPin, OUTPUT); digitalWrite(vccPin, HIGH);
pinMode(gndPin, OUTPUT); digitalWrite(gndPin, LOW);
Serial.println("MAX6675 test");
// wait for MAX chip to stabilize
delay(500);
}
void loop() {
// basic readout test, just print the current temp
Serial.print("C = ");
Serial.println(thermocouple.readCelsius());
Serial.print("F = ");
Serial.println(thermocouple.readFahrenheit());
delay(1000);
}
这是6675库文件自带的。蓝色部分是输出温度值。
请问，问号处是不是设定温度值
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