Question

我已经编程了一台Atmega-16微控制器来连接LM016L LCD显示器。该计划如下：

#include <avr/io.h>
#include <util/delay.h>
#define MrLCDsCrib PORTB
#define DataDir_MrLCDsCrib DDRB
#define MrLCDsControl PORTD
#define DataDir_MrLCDsControl DDRD
#define LightSwitch 5
#define ReadWrite 7
#define BiPolarMood 2

void Check_IF_MrLCD_isBusy(void);
void Peek_A_Boo(void);
void Send_A_Command(unsigned char command);
void Send_A_Character(unsigned char character);

int main(void) {
    DataDir_MrLCDsControl |= 1 << LightSwitch | 1 << ReadWrite | 1 << BiPolarMood;
    _delay_ms(15);

    Send_A_Command(0x01); //Clear Screen 
    _delay_ms(20);
    Send_A_Command(0x38); //8-bit mode
    _delay_ms(20);
    Send_A_Command(0b00001110); // cursor on
    _delay_ms(20);
    Send_A_Command(0x0F); // cursor blinking
    _delay_ms(20);

    Send_A_Character(0x4E); //N
    _delay_ms(20);
    Send_A_Character(0x65); //e
    _delay_ms(20);
    Send_A_Character(0x77); //w
    _delay_ms(20);


    while (1) {}
}

void Check_IF_MrLCD_isBusy() {
    DataDir_MrLCDsCrib = 0;
    MrLCDsControl |= 1 << ReadWrite;
    MrLCDsControl &= ~1 << BiPolarMood;

    while (MrLCDsCrib >= 0x80) {
        Peek_A_Boo();
    }
    DataDir_MrLCDsCrib = 0xFF;
}

//Peek_A_Boo() writes the data to or from the LCD that are waiting to be written 
void Peek_A_Boo() {
    MrLCDsControl |= 1 << LightSwitch;
    asm volatile("nop");
    asm volatile("nop");
    MrLCDsControl &= ~1 << LightSwitch;
}

void Send_A_Command(unsigned char command) {
    Check_IF_MrLCD_isBusy();
    MrLCDsCrib = command;
    MrLCDsControl &= ~ ((1 << ReadWrite) | (1 << BiPolarMood));
    Peek_A_Boo();
    MrLCDsCrib = 0;
}

void Send_A_Character(unsigned char character) {
    Check_IF_MrLCD_isBusy();
    MrLCDsCrib = character;
    MrLCDsControl &= ~ (1 << ReadWrite);
    MrLCDsControl |= 1 << BiPolarMood;
    Peek_A_Boo();
    MrLCDsCrib = 0;
}

当我向LCD发送命令，如使光标闪烁时，它完全正常。但是当调用函数Send_A_Character（）将字符写入屏幕时，它不起作用。我不能让LCD在屏幕上显示任何内容。上面的代码没有语法错误。如果你们中的任何人都指出了一个阻止LCD在屏幕上显示任何内容的逻辑错误，那就太好了。我甚至尝试将每个点的延迟增加到2秒，但这不起作用。

Answer 1

我在这段代码上花费了数小时而无法使其正常工作。但是我设法在我的液晶显示器上写了如下内容：

您需要将LCD的RW连接到MCu的GND
也根据代码修改其他连接。

以下代码对我有用：（http://circuitdigest.com/microcontroller-projects/lcd-interfacing-with-atmega32-avr）

// Code for LCD Interfacing with ATmega32 AVR microcontroller
#include <avr/io.h>
#define F_CPU 1000000UL
#include <util/delay.h>
#define RS 6
#define E  5
void send_a_command (unsigned char command);
void send_a_character(unsigned char character);
int main(void)
{
    DDRA = 0xFF;
    DDRD = 0xFF;
    _delay_ms(50);
    send_a_command(0x01);// sending all clear command
    send_a_command(0x38);// 16*2 line LCD
    send_a_command(0x0E);// screen and cursor ON

     send_a_character (0x44); // ASCII(American Standard Code for Information Interchange) code for 'D'
     send_a_character (0x49); // ASCII(American Standard Code for Information Interchange) code for 'I'
     send_a_character (0x4C); // ASCII(American Standard Code for Information Interchange) code for 'L'
     send_a_character (0x49); // ASCII(American Standard Code for Information Interchange) code for 'I'
     send_a_character (0x50); // ASCII(American Standard Code for Information Interchange) code for 'P'

}
void send_a_command (unsigned char command)
{
    PORTA=command;
    PORTD&= ~(1<<RS);
    PORTD|= (1<<E);
    _delay_ms(50);
    PORTD&= ~(1<<E);
    PORTA =0;
}
void send_a_character (unsigned char character)
{
    PORTA=character;
    PORTD|= (1<<RS);
    PORTD|= (1<<E);
    _delay_ms(50);
    PORTD&= ~(1<<E);
    PORTA =0;
}

Answer 2

如果LCD正确执行命令并且无法显示字符，则需要检查两件事：连接RS引脚。回想一下，对于命令，RS应该是低的，这意味着即使连接错误，命令仍然会运行。您需要确认RS确实是高并且连接正确。我遇到了同样的问题，我花了一天的时间才意识到我确实已经将RS和RW的连接互换到LCD上。数据引脚是正确的，只要它们将命令发送到LCD即可。希望有所帮助：）

LCD遵循命令但不显示字符

2 个答案: