打印温度到LCD外环

Question

我对Arduino或一般的编程是个新手，我正在尝试一些东西。我使用的是一个基本菜单的代码，你只需按下按钮就可以滚动浏览。这很好用，但我想让它在第一个菜单上显示温度。

计算温度的代码在循环()中，而定制菜单的代码在setup()和loop()之前。我想使用lcd.print(temperatureC)将温度打印到LCD，但不能使用temperatureC，因为它只在loop()中声明。

有什么办法可以解决这个问题吗？我对此非常陌生。

#include <LiquidCrystal.h>

LiquidCrystal lcd(8,9,10,11,12,13);
int tempPin = A0;
int photocellPin = A1;
const byte mySwitch = 7;
#define aref_voltage 3.3


// these "states" are what screen is currently being displayed.
typedef enum 
  {
  POWER_ON, TEMPERATURE, LIGHTSENSOR, EXHAUST_FAN1, EXHAUST_FAN2,
  // add more here ...

  LAST_STATE  // have this last
  } states;

byte state = POWER_ON;

byte oldSwitch = HIGH;

void powerOn ()
  {
  Serial.println ("Welcome!");
  lcd.setCursor(0,0);
  lcd.print("Welcome!");
  delay(2000);

  }

void showTemperature ()
  {
  Serial.println ("Temperature");
  lcd.clear();
  lcd.setCursor(0,0);
  lcd.print("Temperature");
  lcd.setCursor(0,1);
  lcd.print(temperatureC);



void setup()
{
  Serial.begin(9600);  //Start the serial connection with the computer
                       //to view the result open the serial monitor 
  analogReference(EXTERNAL);
  pinMode (mySwitch, INPUT_PULLUP);
  lcd.begin(16, 2);
  lcd.clear();
  powerOn ();
}

void loop()
{ 
  int sensorVal = analogRead(tempPin);
  delay(5);
  int photocellVal = analogRead(photocellPin);
  delay(5);
  float voltage = (sensorVal) * aref_voltage;
  voltage /= 1024.0; 
  float temperatureC = (voltage - .5) * 100;
  temperatureC = round(temperatureC * 2.0) / 2.0;

  {
  byte switchValue = digitalRead (mySwitch);

  // detect switch presses
  if (switchValue != oldSwitch)
    {
    delay (100);   // debounce

    // was it pressed?
    if (switchValue == LOW)
      {
      state++;      // next state
      if (state >= LAST_STATE)
        state = TEMPERATURE;  

      switch (state)
        {
        case POWER_ON:     powerOn ();         break;
        case TEMPERATURE:  showTemperature (); break;
        case LIGHTSENSOR:  showLightsensor (); break;
        case EXHAUST_FAN1: showExhaustFan1 (); break;
        case EXHAUST_FAN2: showExhaustFan2 (); break;
        }  // end of switch
      }  // end of switch being pressed

    oldSwitch = switchValue;  
    } // end of switch changing state

  }  // end of loop

Answer 1

将读取温度的代码移动到它自己的方法中，(与轻量读取代码分开-为此创建另一个方法)……

float getTemperature() {
  int sensorVal = analogRead(tempPin);
  delay(5);
  float voltage = (sensorVal) * aref_voltage;
  voltage /= 1024.0; 
  float temperatureC = (voltage - .5) * 100;
  temperatureC = round(temperatureC * 2.0) / 2.0;
  return temperatureC;
}

然后在showTemperature()方法中调用此方法。