如何通过键盘将文本写到液晶屏幕上，然后记住文本以供比较

Question

我在使用16x2 I2C液晶显示屏时遇到了问题。

下面是我需要做的步骤:1.将一个数字值通过键盘输入到屏幕的顶部。此数值不应超过3位数。2.当*键被按一次时，键盘应该是活动的(和屏幕可编辑的)。3.当按一次#键时，键盘应再次处于不活动状态。4.无论在屏幕上放置了什么值，都应该记住，因此，当传感器运行时，它应该能够将其值与屏幕值进行比较，从而实现核心进程停止的平等。

下面是我的代码，这不是我的工作。有人能提出解决办法吗？谢谢。

#include <Keypad.h>
#include <LiquidCrystal_I2C.h> 
#include <Wire.h>

LiquidCrystal_I2C lcd(0x27, 16, 4); 

#include<stdio.h>
const int ROW_NUM = 4; 
const int COLUMN_NUM = 3; 
char keys[ROW_NUM][COLUMN_NUM] = {
{'1','2','3'}, 
{'4','5','6'},
{'7','8','9'},
{'*','0','#'},
};
byte pin_rows[ROW_NUM] = {8,7,6,5}; 
byte pin_column[COLUMN_NUM] = {4,3,2}; 
Keypad keypad = Keypad( makeKeymap(keys), pin_rows, pin_column, ROW_NUM, COLUMN_NUM );

int counter = 0;

void setup() {
  // put your setup code here, to run once:
lcd.init(); 
  lcd.clear();
  lcd.backlight();
  lcd.setCursor(0, 0); 
  lcd.print("Volume.        ml");
   lcd.setCursor(0, 1); 
   lcd.print("Filled        ml");
  

}


void loop() {
  // put your main code here, to run repeatedly:
  keypadfunction();

}

void keypadfunction()
{
  char key = keypad.getKey();

  if (key)
  {
    
  }
  if (key == '*')
  {
    while (key != '#' || counter <=3)
    {
      lcd.setCursor(8, 1);
      lcd.setCursor(8+counter, 1); 
      lcd.print(key);
      counter = counter+1;
    }
  }
}

@C1sc0建议后的更改：

#include <Keypad.h>
#include <LiquidCrystal_I2C.h> 
#include <Wire.h>
 
LiquidCrystal_I2C lcd(0x27, 16, 4); 

#include<stdio.h>
const int ROW_NUM = 4; 
const int COLUMN_NUM = 3; 
char keys[ROW_NUM][COLUMN_NUM] = {
{'1','2','3'},
{'4','5','6'},
{'7','8','9'},
{'*','0','#'},
};
byte pin_rows[ROW_NUM] = {8,7,6,5}; 
byte pin_column[COLUMN_NUM] = {4,3,2}; 
Keypad keypad = Keypad( makeKeymap(keys), pin_rows, pin_column, 
ROW_NUM, COLUMN_NUM );

char volume[3];
byte volumeCount = 0;
bool edit = 0;
int finalValue = 0;


void setup() 
{
  // put your setup code here, to run once:
lcd.init(); 
  lcd.clear();
  lcd.backlight();
  lcd.setCursor(0, 0); 
  lcd.print("Volume        ml");
   lcd.setCursor(0, 1); 
   lcd.print("Filled        ml");


}


void loop() 
{
char key = keypad.getKey();

  if(key) // check if any key was pressed
  {
    if(key == '*') // if * was pressed switch to edit mode
    {
        lcd.setCursor(0,0); // set your cursor at columnt 0, row 0
        lcd.clear();
        lcd.print("Enter volume: ");
        edit = true;
        lcd.setCursor(0,1); // set your cursor to second row 
        volumeCount = 0;
        volume[0] = '0';
        volume[1] = '0';
        volume[2] = '0';
    }

    if(edit && volumeCount < 3) // enter edit mode
    {
        volume[volumeCount] = key; // save key to a char array
        lcd.setCursor(volumeCount,1);  // set your cursor to the 
next position
        lcd.print(volume[volumeCount]); // print the pressed button to lcd
        volumeCount++; // increment the array index (cursor position)
    }

    if(volumeCount == 3 || key == '#') // array.length == 3 OR you pressed #
    {
        edit = false; // disable edit mode
        volumeCount = 0; // reset your counter
    lcd.setCursor(0,0);
    lcd.clear();//new
    lcd.print(volume); 
    finalValue = atoi(volume); // save your entered value for further usage
    //volume[0] = '0';
    //volume[1] = '0';
    //volume[2] = '0';
    }
  }

  buttonState1 = digitalRead(buttonPin1);
    if (buttonState1 == HIGH)
    {
     //do process basis 'finalValue'
    }


}

屏幕输出

Answer 1

创建bool (或字节)变量，以发出“编辑”状态的信号

if (key == '*') { edit= true; }

在循环中(这将是您的第一个if条件)。

创建另一个if，在这里检查编辑标志(如果为真，则等待这3个值。您可以读取char数组的按下键。

char values[3]; //在安装程序()之前创建此变量

在这里，对于索引，您可以使用一个counter (正如我看到的，它已经存在于您的代码中)。因此，将所有这些行放在第二个if条件中，并在这里将计数器增加一个。您也可以在这里显示输入的字符：

lcd.setCursor(8+counter, 1);
lcd.print(key);

创建第三个if块，并检查计数器是# key or counter == 3。如果满足这个条件，您必须做三件事，将计数器重置为零，将编辑状态重置为false，最后将值转换为int (带有atoi函数)。

工作之后，您可以重构代码，使其更有效/更易读。

你需要这样的东西：

char volume[3];
byte volumeCount = 0;
bool edit = 0;
int finalValue = 0;
void loop() 
{

  
  
  char key = keypad.getKey();
  
  if(key) // check if any key was pressed
  {
    if(key == '*') // if * was pressed switch to edit mode
    {
        lcd.setCursor(0,0); // set your cursor at columnt 0, row 0
        lcd.print("Enter volume: ");
        edit = true;
        lcd.setCursor(0,1); // set your cursor to second row 
        volumeCount = 0;
        volume[0] = '0'; 
        volume[1] = '0'; 
        volume[2] = '0';
    }
    
    if(edit && volumeCount < 3 && key != '*' && key != '#')
    {
        volume[volumeCount] = key; // save key to a char array
        lcd.setCursor(volumeCount,1);  // set your cursor to the next position
        lcd.print(volume[volumeCount]); // print the pressed button to lcd
        volumeCount++; // increment the array index (cursor position)
    }
    
    if(volumeCount == 3 || key == '#') // array.length == 3 OR you pressed #
    {
        edit = false; // disable edit mode
        volumeCount = 0; // reset your counter
        finalValue = atoi(volume); // save your entered value for further usage
        volume[0] = '0'; 
        volume[1] = '0'; 
        volume[2] = '0'; # ty for the fix!!!
    }
  }
  
  
  
  
}