lcd_test.c

#include "lcd_test.h"

#define FCY 16000000UL
#include <libpic30.h>

#define LCD_RS LATBbits.LATB15
#define LCD_RW LATDbits.LATD5
#define LCD_E LATDbits.LATD4
#define LCD_DATA PORTE
#define LCD_DATA_TRIS TRISE

static void lcd_enable();
static uint8_t is_lcd_busy();
static void lcd_send_cmd(uint8_t cmd);

void lcd_setup() {
    // Pin 44, RB15, AN15, LCD_RS
    TRISBbits.TRISB15 = 0;
    ANSBbits.ANSB15 = 0;
    LATBbits.LATB15 = 0;
    // Pin 82, RD5, LCD_RW
    TRISDbits.TRISD5 = 0;
    LATDbits.LATD5 = 0;
    // Pin 81, RD4, LCD_E
    TRISDbits.TRISD4 = 0;
    LATDbits.LATD4 = 0;
    // Pin 93, RE0, LCD_D0
    TRISEbits.TRISE0 = 0;
    LATEbits.LATE0 = 0;
    // Pin 94, RE1, LCD_D1
    TRISEbits.TRISE1 = 0;
    LATEbits.LATE1 = 0;
    // Pin 98, RE2, LCD_D2
    TRISEbits.TRISE2 = 0;
    LATEbits.LATE2 = 0;
    // Pin 99, RE3, LCD_D3
    TRISEbits.TRISE3 = 0;
    LATEbits.LATE3 = 0;
    // Pin 100, RE4, LCD_D4
    TRISEbits.TRISE4 = 0;
    LATEbits.LATE4 = 0;
    // Pin 3, RE5, LCD_D5
    TRISEbits.TRISE5 = 0;
    LATEbits.LATE5 = 0;
    // Pin 4, RE6, LCD_D6
    TRISEbits.TRISE6 = 0;
    LATEbits.LATE6 = 0;
    // Pin 5, RE7, LCD_D7
    TRISEbits.TRISE7 = 0;
    LATEbits.LATE7 = 0;

    __delay_ms(100);

    // Set display settings
    lcd_clear();

    // Set cursor to inc, display shift off
    // 0b 000001 ID S. ID 1 = inc address (cursor goes right), ID 0 = dec address (cursor goes left). S 1 = shift, 0 = no shift
    lcd_send_cmd(0b00000110);

    // Set display type to 8 wire connection, dual line mode, 5x8 dots
    // 0b 0 0 1 DL N F x x.   DL 1 = 8 wires, 0 = 4 wires. N 1 = 2 line display. 0 = 1 line display. F 1 = 5x10 dots, 0 = 5x8 dots
    lcd_send_cmd(0b00111000);

    // Turn on display, turn off cursor, turn off blink
    // 0b00001 D C B. D = Display, C = Cursor, B = Blink. 1= ON 0 = OFF
    lcd_send_cmd(0b00001100);
}

static void lcd_enable() {
    LCD_E = 1;
    __delay_us(1);
    //delay_1us();
    LCD_E = 0;
}

//Returns 1 if busy, 0 if ready
static uint8_t is_lcd_busy() {
    // Set data lines as inputs
    LCD_DATA_TRIS = 0b11111111;
    // RW==1 : Read data
    LCD_RW =  1;
    // 0 = command, 1 = data
    LCD_RS = 0;
    // Pulse the enable line for 1us
    LCD_E = 1;
    __delay_us(1);
    // Read data from LCD
    uint16_t lcd_read_val = LCD_DATA;
    LCD_E = 0;
    // Set data lines as outputs
    LCD_DATA_TRIS = 0;
    // If MSB = 1 then return 1, else return 0
    return ((lcd_read_val & 0b10000000) == 0b10000000);
}

static void lcd_send_cmd(uint8_t cmd) {
   // loop until LCD ready
   while(is_lcd_busy());
   // Set data lines as inputs
   LCD_DATA_TRIS = 0;
   // Set to write mode
   LCD_RW = 0;
   // 0 = command, 1 = data
   LCD_RS = 0;
   // Set data lines to cmd
   LCD_DATA = cmd;
   // Pulse the enable for 1 us
   lcd_enable();
}

void lcd_send_char(uint8_t data) {
    // Wait until LCD is not busy
    while(is_lcd_busy());
    // Set data lines to inputs
    LCD_DATA_TRIS = 0;
    // Set to write mode
    LCD_RW = 0;
    // Set to data mode
    LCD_RS = 1;
    // Set data lines to data
    LCD_DATA = data;
    // Pulse the enable line for 1us
    lcd_enable();
}

void lcd_send_string(const uint8_t *var) {
    // While *var != 0 send *var and inc to next char
    while(*var) {
        lcd_send_char(*var++);
    }
}

void lcd_set_cursor(uint8_t row, uint8_t column) {
    if (row == 1) {
        // Set DRAM address 0b1xxxxxxx = row 1, 0b10000000 = Row 1 column 1, 0b10000001 = row 1, column 2, etc
        lcd_send_cmd(0b10000000 + (column-1));
    } else if (row==2) {
        // Set DRAM address 0b11xxxxxx = row 2
        lcd_send_cmd(0b11000000 + (column-1));
    }
}

void lcd_home() {
    // Sets DRAM to address 0, and returns display from being shifted
    lcd_send_cmd(0b00000010);
}

void lcd_clear() {
    // Clears all DRAM, sets DRAM address to 0
    lcd_send_cmd(0b00000001);
}

void lcd_cursor_shift(uint8_t direction) {
    // Sends command to shift cursor
    // Bit 2 = 0 = Shift right. // Bit 2 = 1 = Shift left
    lcd_send_cmd(0b00010000 | direction);
}

void lcd_screen_shift(uint8_t direction) {
    //Sends command to shift display
    lcd_send_cmd(0b00011000 | direction);
}

// Custom char generator: https://www.quinapalus.com/hd44780udg.html
void lcd_add_char(uint8_t address,
                  uint8_t line0, uint8_t line1, uint8_t line2, uint8_t line3,
                  uint8_t line4, uint8_t line5, uint8_t line6, uint8_t line7) {

    // Set address to CGRAM. CHAR0 is at 0x40, CHAR1 is at 0x48,
    // CHAR2 is at 0x56, etc. 8 CHARS can be stored
    lcd_send_cmd(0x40 + address);       
    // Send line one of char 0bXXX11111. 3MSBs are ignored
    lcd_send_char(line0);               
    // Send line two of char 0bXXX11111. 3MSBs are ignored
    lcd_send_char(line1);               
    // etc
    lcd_send_char(line2);               
    lcd_send_char(line3);
    lcd_send_char(line4);
    lcd_send_char(line5);
    lcd_send_char(line6);
    lcd_send_char(line7);
    // Set address back to DRAM, location 1,1
    lcd_send_cmd(0b10000000);           
}

lcd_test.h

#ifndef LCD_TEST_H
#define	LCD_TEST_H

#include "xc.h"
#define LCD_SHIFT_RIGHT 0b00000100
#define LCD_SHIFT_LEFT 0b00000000

void lcd_setup();
void lcd_send_string(const uint8_t *var);
void lcd_send_char(uint8_t data);
void lcd_set_cursor(uint8_t row, uint8_t column);
void lcd_home();
void lcd_clear();
void lcd_cursor_shift(uint8_t direction);
void lcd_screen_shift(uint8_t direction);
void lcd_add_char(uint8_t address,
                  uint8_t line0, uint8_t line1, uint8_t line2, uint8_t line3,
                  uint8_t line4, uint8_t line5, uint8_t line6, uint8_t line7);
#endif