LCD.rar_pic18f

/* - - - - - - - LCD interface - - - - - - - - - * This code will interface to a standard LCD controller * It uses it in 4 or 8 bit mode. */ #include <pic18.h> #include "lcd.h" static bit fourbit; // four or eight bit mode? #ifdef CHECKBUSY unsigned char lcd_read_cmd_nowait(void) { unsigned char c, readc; LCD_DATA_TRIS = INPUT_DATA; LCD_RW = 1; // Read LCD asm("nop"); // short propagation delay asm("nop"); // short propagation delay if (fourbit) { LCD_STROBE_READ(readc); // Read high nibble // Move 4 bits to high nibble while zeroing low nibble c = ( ( readc << 4 ) & 0xF0 ); LCD_STROBE_READ(readc); // Read low nibble c |= ( readc & 0x0F ); // Or in 4 more bits to low nibble } else { LCD_STROBE_READ(readc); c = readc; } LCD_RW = 0; // Return to default mode of writing LCD LCD_DATA_TRIS = OUTPUT_DATA; // Return to default mode of writing LCD return(c); } /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */ void lcd_check_busy(void) // Return when the LCD is no longer busy, { //or we've waiting long enough! // To avoid hanging forever in event there's a bad or // missing LCD on hardware. Will just run SLOW, but still run. unsigned int retry; unsigned char c; for (retry=1000; retry-- > 0; ) { c = lcd_read_cmd_nowait(); if (0==(c&0x80)) break; // Check busy bit. If zero, no longer busy } } #endif /* - - - - - - send a command to the LCD - - - - - - - - */ void lcd_cmd(unsigned char c) { LCD_WAIT; // may check LCD busy flag, or just delay a little, depending on lcd.h if (fourbit) { LCD_DATA = ( ( c >> 4 ) & 0x0F ); LCD_STROBE(); LCD_DATA = ( c & 0x0F ); LCD_STROBE(); } else { LCD_DATA = c; LCD_STROBE(); } } /* - - - - - - - - - send data to the LCD - - - - - - - -*/ void lcd_data(unsigned char c) { LCD_WAIT; // may check LCD busy flag, or just delay a little, depending on lcd.h LCD_DATA = 0; LCD_RS = 1; if (fourbit) { LCD_DATA |= ( ( c >> 4 ) & 0x0F ); LCD_STROBE(); LCD_DATA &= 0xF0; LCD_DATA |= ( c & 0x0F ); LCD_STROBE(); } else { LCD_DATA = c; LCD_STROBE(); } LCD_RS = 0; } /* - - - - - - - write a string of chars to the LCD - - - - - - */ void lcd_puts(const char * s) { while(*s) lcd_data(*s++); } /* - - - - - - initialize the LCD - - - - - - - - */ void lcd_init(unsigned char mode) { char init_value; fourbit = 0; if (mode == FOURBIT_MODE){ fourbit = 1; init_value = 0x3; }else{ init_value = 0x3F; } LCD_RS = 0; LCD_EN = 0; LCD_RW = 0; LCD_RS_TRIS = OUTPUT_PIN; LCD_EN_TRIS = OUTPUT_PIN; LCD_RW_TRIS = OUTPUT_PIN; LCD_DATA_TRIS = OUTPUT_DATA; DelayMs(15); LCD_DATA = init_value; LCD_STROBE(); DelayMs(5); LCD_DATA = init_value; LCD_STROBE(); DelayUs(200); LCD_DATA = init_value; LCD_STROBE(); if (fourbit){ LCD_WAIT; //may check LCD busy flag, or just delay a little, depending on lcd.h LCD_DATA = 0x2; // Set 4-bit mode LCD_STROBE(); lcd_cmd(0x28); // Function Set }else{ lcd_cmd(0x38); } lcd_cmd(0xF); //Display On, Cursor On, Cursor Blink lcd_cmd(0x1); //Display Clear lcd_cmd(0x6); //Entry Mode lcd_cmd(0x80); //Initialize DDRAM address to zero } /* - - - - - - - - - Delay functions - - - - - - - - - - * * See delay.h for details * Make sure this code is compiled with full optimization!!! */ void DelayMs(unsigned char cnt) { unsigned char i; while (cnt--) { i=4; while(i--) { DelayUs(uS_CNT); /* Adjust for error */ } ; } ; }