lcd.lst

本程式通过4*4键盘的输入控制步进马达的正转和反转,停止转动以及加速和减速.

     1: 
     2:  /*     LCD interface example
     3:  *      Uses routines from delay.c
     4:  *      This code will interface to a standard LCD controller
     5:  *      like the Hitachi HD44780. It uses it in 4 bit mode, with
     6:  *      the hardware connected as follows (the standard 14 pin 
     7:  *      LCD connector is used):
     8:  *      
     9:  *      PORTB bits 0-3 are connected to the LCD data bits 4-7 (high nibble)
    10:  *      PORTA bit 4 is connected to the LCD RS input (register select)
    11:  *      PORTB bit 3 is connected to the LCD EN bit (enable)
    12:  *      
    13:  *      To use these routines, set up the port I/O (TRISA, TRISB) then
    14:  *      call lcd_init(), then other routines as required.
    15:  *      
    16:  */
    17: #ifndef XTAL FREQ
    18: #define XTAL_FREQ       4MHZ            /* Crystal frequency in MHz */
    19: #endif
    20: 
    21: #include        <pic.h>
    22: #include        "lcd.h"
    23: #include        "delay.h"
    24: 
    25:  
    26: #define PORTBIT(adr, bit)       ((unsigned)(&adr)*8+(bit)) 
    27:  
    28: static bit LCD_RS       @ PORTBIT(PORTA, 4);    // Register select
    29: static bit LCD_EN       @ PORTBIT(PORTB, 3);    // Enable
    30: static bit      spkr  @ PORTBIT(PORTA, 0);
    31: 
    32: 
    33: void
    34: lcd_strobe(void)
    35: {
    36:         LCD_EN = 1      ;
    37:         DelayUs(1);
    38:         LCD_EN = 0      ;
    39:         DelayUs(1);
    40: }
    41: 
    42: void
    43: lcd_write(unsigned char c)
    44: {
    45:         PORTB = (PORTB & 0x0F) |  (c & 0xF0);           /*es. A=65 =>0100 0001 bin  >>4 avremo 0000 0100 or PORTB&11110000 */
    46:         lcd_strobe();
    47:         PORTB = (PORTB & 0x0F) |  (c << 4);     /* 0100 0001 & 00001111 = 0000 0001 */ 
    48:         lcd_strobe();
    49:         DelayUs(50);
    50: }
    51: 
    52: /*
    53:  *      Clear and home the LCD
    54:  */
    55: 
    56: void
    57: lcd_clear(void)
    58: {
    59:         LCD_RS = 0;
    60:         lcd_write(0x1);
    61:         DelayMs(2);
    62: }
    63: 
    64: /* write a string of chars to the LCD */
    65: 
    66: void
    67: lcd_puts(const char * s)
    68: {
    69:         LCD_RS = 1;     // write characters
    70:         while(*s)
    71:                 lcd_write(*s++);
    72: }
    73: 
    74: /* write one character to the LCD */
    75: 
    76: void
    77: lcd_putch(char c)
    78: {
    79:         LCD_RS = 1;     // write characters
    80:         PORTB = (PORTB & 0x0F) |  (c & 0xF0);
    81:         lcd_strobe();
    82:         PORTB = (PORTB & 0x0F) |  (c << 4);
    83:         lcd_strobe();
    84:         DelayUs(40);
    85: }
    86: 
    87: 
    88: /*
    89:  * Go to the specified position
    90:  */
    91: 
    92: void
    93: lcd_goto(unsigned char pos)
    94: {
    95:         LCD_RS = 0;
    96:         lcd_write(0x80+pos);
    97: }
    98:         
    99: /* initialise the LCD - put into 4 bit mode */
   100: 
   101: void
   102: lcd_init(void)
   103: {
   104:         LCD_RS = 0;     // write control bytes 'comando'
   105:         DelayMs(50);    // power on delay
   106:         PORTB = 0x30;   // attention!
   107:         lcd_strobe();
   108:         DelayMs(5);
   109:         lcd_strobe();
   110:         DelayUs(100);
   111:         lcd_strobe();
   112:         DelayMs(1);
   113:         PORTB = 0x20;   // set 4 bit mode
   114:         lcd_strobe();
   115:         DelayMs(1);
   116:         lcd_write(0x28);        // 4 bit mode, 1/16 duty, 5x8 font
   117:         lcd_write(0x06);        // entry mode
   118:         lcd_write(0x0C);        // display on
   119:         lcd_clear();    // clear
   120: 
   121: }
   122: