无法使用 PIC18F4620 初始化 Qapass 1602A LCD

Question

我无法使用 PIC18F4620 初始化 QAPASS 1602A LCD，我总是在两条线上得到方形块。一开始以为是液晶屏坏了，换了个新的，结果还是一样。我使用通过 PICkit3 连接到 PC 的 logifind PIC 40 Mini 开发板，其他一切在每个端口上都工作正常，但不是 LCD。

非常感谢您的帮助。

//main.c
#include "newxc8_header.h"
#include <xc.h>
#include "lcd_16x2.h"

void main(void) {
    ADCON1=0x0F; //configuring all analog ports to digital
    TRISB=0x00; //Set RBs as output
    TRISD=0x00; //Set RDs as output
    TRISE=0x00; //Set REs as output

    LCD_Init();  //Initialize 16x2 LCD

    LCD_String("Hello");
    while(1);
}


//lcd_16x2.c
#include "lcd_16x2.h"

void LCD_Init(void)
{
    __delay_ms(1000);
    EN = 0;
    RS = 0;
    ldata = 0x00;
    LCD_Command(0x38);  // Initialization of 16X2 LCD: 8-bit, 2 Lines, 5x7 Dots
    LCD_Command(0x0C);  // Display ON Cursor OFF
    LCD_Command(0x01);   //clear LCD
    LCD_Command(0x02);   //cursor beginning first line
}

void LCD_Command(unsigned char cmd)
{
    ldata = cmd;  /* Send data to PORT as a command for LCD */
    RS = 0;  /* Command Register is selected */
    EN = 1;  /* High-to-Low pulse on Enable pin to latch data */
    __delay_ms(5);
    EN = 0;
    __delay_ms(3);
}

void LCD_Char(unsigned char data)
{
    ldata = data;  /* Send data to LCD */  
    RS = 1;  // Data Register is selected */
    EN = 1;  // High-to-Low pulse on Enable pin to latch data */   
    __delay_ms(5);
    EN = 0;
    __delay_ms(3);
}

void LCD_String(const char *msg)
{
    while(*msg != 0)
    {
      LCD_Char(*msg);
      msg++;
    }
}

//lcd_16x2.h
#ifndef LCD_16X2_H
#define LCD_16X2_H

#ifdef  __cplusplus
extern "C" {
#endif

#include <xc.h>

#define _XTAL_FREQ 16000000 //16 MHz (4 MHz x 4 PLL)

#define ldata LATB                  /*PORTB(RB0-RB7) is used for transmitting data to LCD*/
#define RS LATEbits.LATE0           /*RE0 pin is used for Register Select*/
#define EN LATEbits.LATE1           /*RE1 pin is used for Enable*/

void LCD_Init(void);
void LCD_Command(unsigned char );
void LCD_Char(unsigned char x);
void LCD_String(const char *);
void LCD_Clear();

#ifdef  __cplusplus
}
#endif

#endif  /* NEWFILE_H */

Answer 1

您的问题没有包含足够的详细信息来确定答案。

最好的猜测是您的 LogiFind PIC-40-MINI 板之间存在接线错误： 和您的 QAPASS 1602A LCD 模块： 一张他们如何联系的照片会很有帮助。

如果您确信接线正确，则 LCD_Init() 函数可能存在问题，请参阅第 45 页的HD44780 data sheet 了解有关在 8 位并行模式下或在您未发布的代码中初始化模块的流程图.

添加于 2020 年 1 月 19 日：

我按照你的描述组装了一个 PIC18F4620 和 LCD 模块。

发现您发布的代码没有显示您正在使用的配置字。

在默认频率 (1MHz) 下使用内部振荡器时，您的代码运行但比预期慢 16 倍。

调整一些设置后，这是代码的最终版本：

//main.c

// PIC18F4620 Configuration Bit Settings

// 'C' source line config statements

// CONFIG1H
#pragma config OSC = INTIO67    // Oscillator Selection bits (Internal oscillator block, port function on RA6 and RA7)
#pragma config FCMEN = OFF      // Fail-Safe Clock Monitor Enable bit (Fail-Safe Clock Monitor disabled)
#pragma config IESO = OFF       // Internal/External Oscillator Switchover bit (Oscillator Switchover mode disabled)

// CONFIG2L
#pragma config PWRT = OFF       // Power-up Timer Enable bit (PWRT disabled)
#pragma config BOREN = OFF      // Brown-out Reset Enable bits (Brown-out Reset disabled in hardware and software)
#pragma config BORV = 3         // Brown Out Reset Voltage bits (Minimum setting)

// CONFIG2H
#pragma config WDT = OFF        // Watchdog Timer Enable bit (WDT disabled (control is placed on the SWDTEN bit))
#pragma config WDTPS = 32768    // Watchdog Timer Postscale Select bits (1:32768)

// CONFIG3H
#pragma config CCP2MX = PORTC   // CCP2 MUX bit (CCP2 input/output is multiplexed with RC1)
#pragma config PBADEN = OFF     // PORTB A/D Enable bit (PORTB<4:0> pins are configured as digital I/O on Reset)
#pragma config LPT1OSC = OFF    // Low-Power Timer1 Oscillator Enable bit (Timer1 configured for higher power operation)
#pragma config MCLRE = ON       // MCLR Pin Enable bit (MCLR pin enabled; RE3 input pin disabled)

// CONFIG4L
#pragma config STVREN = ON      // Stack Full/Underflow Reset Enable bit (Stack full/underflow will cause Reset)
#pragma config LVP = OFF        // Single-Supply ICSP Enable bit (Single-Supply ICSP disabled)
#pragma config XINST = OFF      // Extended Instruction Set Enable bit (Instruction set extension and Indexed Addressing mode disabled (Legacy mode))

// CONFIG5L
#pragma config CP0 = OFF        // Code Protection bit (Block 0 (000800-003FFFh) not code-protected)
#pragma config CP1 = OFF        // Code Protection bit (Block 1 (004000-007FFFh) not code-protected)
#pragma config CP2 = OFF        // Code Protection bit (Block 2 (008000-00BFFFh) not code-protected)
#pragma config CP3 = OFF        // Code Protection bit (Block 3 (00C000-00FFFFh) not code-protected)

// CONFIG5H
#pragma config CPB = OFF        // Boot Block Code Protection bit (Boot block (000000-0007FFh) not code-protected)
#pragma config CPD = OFF        // Data EEPROM Code Protection bit (Data EEPROM not code-protected)

// CONFIG6L
#pragma config WRT0 = OFF       // Write Protection bit (Block 0 (000800-003FFFh) not write-protected)
#pragma config WRT1 = OFF       // Write Protection bit (Block 1 (004000-007FFFh) not write-protected)
#pragma config WRT2 = OFF       // Write Protection bit (Block 2 (008000-00BFFFh) not write-protected)
#pragma config WRT3 = OFF       // Write Protection bit (Block 3 (00C000-00FFFFh) not write-protected)

// CONFIG6H
#pragma config WRTC = OFF       // Configuration Register Write Protection bit (Configuration registers (300000-3000FFh) not write-protected)
#pragma config WRTB = OFF       // Boot Block Write Protection bit (Boot Block (000000-0007FFh) not write-protected)
#pragma config WRTD = OFF       // Data EEPROM Write Protection bit (Data EEPROM not write-protected)

// CONFIG7L
#pragma config EBTR0 = OFF      // Table Read Protection bit (Block 0 (000800-003FFFh) not protected from table reads executed in other blocks)
#pragma config EBTR1 = OFF      // Table Read Protection bit (Block 1 (004000-007FFFh) not protected from table reads executed in other blocks)
#pragma config EBTR2 = OFF      // Table Read Protection bit (Block 2 (008000-00BFFFh) not protected from table reads executed in other blocks)
#pragma config EBTR3 = OFF      // Table Read Protection bit (Block 3 (00C000-00FFFFh) not protected from table reads executed in other blocks)

// CONFIG7H
#pragma config EBTRB = OFF      // Boot Block Table Read Protection bit (Boot Block (000000-0007FFh) not protected from table reads executed in other blocks)

#include <xc.h>
#include "lcd_16x2.h"

void main(void) {
    OSCCON  = 0b01100000;   // sets clock = 4MHz
    OSCTUNE = 0b01000000;   // turn on 4xPLL

    ADCON1=0x0F; //configuring all analog ports to digital
    TRISB=0x00; //Set RBs as output
    TRISD=0x00; //Set RDs as output
    TRISE=0x00; //Set REs as output

    LCD_Init();  //Initialize 16x2 LCD

    LCD_Command(0x80);
    LCD_String("Hello");
    LCD_Command(0xC0);
    LCD_String(__TIME__ " v1 ");
    while(1);
}

//lcd_16x2.c
#include <xc.h>
#include "lcd_16x2.h"

void LCD_Init(void)
{
    __delay_ms(1000);
    EN = 0;
    RS = 0;
    LCD_Command(0x38);  // Initialization of 16X2 LCD: 8-bit, 2 Lines, 5x7 Dots
    LCD_Command(0x0C);  // Display ON Cursor OFF
    LCD_Command(0x01);   //clear LCD
    LCD_Command(0x02);   //cursor beginning first line
}

void LCD_Command(unsigned char cmd)
{
    ldata = cmd;  /* Send data to PORT as a command for LCD */
    RS = 0;  /* Command Register is selected */
    EN = 1;  /* High-to-Low pulse on Enable pin to latch data */
    __delay_us(1);
    EN = 0;
    __delay_ms(4);
}

void LCD_Char(unsigned char data)
{
    ldata = data;  /* Send data to LCD */  
    RS = 1;  // Data Register is selected */
    EN = 1;  // High-to-Low pulse on Enable pin to latch data */   
    __delay_us(1);
    EN = 0;
    __delay_us(50);
}

void LCD_String(const char *msg)
{
    while(*msg != 0)
    {
      LCD_Char(*msg);
      msg++;
    }
}

//lcd_16x2.h
#ifndef LCD_16X2_H
#define LCD_16X2_H

#ifdef  __cplusplus
extern "C" {
#endif

#include <xc.h>

#define _XTAL_FREQ 16000000 //16 MHz (4 MHz x 4 PLL)

#define ldata LATB                  /*PORTB(RB0-RB7) is used for transmitting data to LCD*/
#define RS LATEbits.LATE0           /*RE0 pin is used for Register Select*/
#define EN LATEbits.LATE1           /*RE1 pin is used for Enable*/

void LCD_Init(void);
void LCD_Command(unsigned char );
void LCD_Char(unsigned char x);
void LCD_String(const char *);
void LCD_Clear();

#ifdef  __cplusplus
}
#endif

#endif  /* NEWFILE_H */