Create LCD driver
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99e3a82c4c
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GPG Key ID:
5CCFC80B0B47B04B
2
.gitignore
vendored
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2
.gitignore
vendored
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*.o
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rpi4b-temp-humidity
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13
Makefile
13
Makefile
@ -2,15 +2,20 @@ CC=clang
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CFLAGS=-std=c99
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LD=clang
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LDFLAGS=-lgpio
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OBJS=main.o lcd.o
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OBJS=main.o util.o lcd.o
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OUTFILE=rpi4b-temp-humidity
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${OUTFILE}: ${OBJS}
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${LD} ${LDFLAGS} -o $@ ${OBJS}
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main.o lcd.o: lcd.h
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rpi4b-temp-himidity: ${OBJS}
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${LD} ${LDFLAGS} -o $@ ${OBJS}
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main.o util.o lcd.o: util.h
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.c.o:
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${CC} ${CFLAGS} -c $<
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clean:
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rm -f ${OUTFILE} ${OBJS}
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.SUFFIXES: .c .o
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.PHONY: clean
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140
lcd.c
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140
lcd.c
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/*
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* lcd.c - Subroutines for communicating with HD44780U based LCD panels
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* Copyright (C) 2024 Alexander Rosenberg
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*
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* This program is free software: you can redistribute it and/or modify it under
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* the terms of the GNU General Public License as published by the Free Software
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* Foundation, either version 3 of the License, or (at your option) any later
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* version. See the LICENSE file for more information.
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*
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* This file was created with help from the document located here:
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* https://www.sparkfun.com/datasheets/LCD/HD44780.pdf
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*/
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#include "lcd.h"
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#include "util.h"
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#include <unistd.h>
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static void lcd_set_read(LCD *lcd, bool is_read, bool force) {
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if (force || lcd->is_read != is_read) {
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gpio_config_t cfg = {.g_flags = is_read ? GPIO_PIN_INPUT
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: GPIO_PIN_OUTPUT};
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cfg.g_pin = lcd->d0;
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gpio_pin_set_flags(lcd->handle, &cfg);
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cfg.g_pin = lcd->d1;
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gpio_pin_set_flags(lcd->handle, &cfg);
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cfg.g_pin = lcd->d2;
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gpio_pin_set_flags(lcd->handle, &cfg);
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cfg.g_pin = lcd->d3;
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gpio_pin_set_flags(lcd->handle, &cfg);
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cfg.g_pin = lcd->d4;
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gpio_pin_set_flags(lcd->handle, &cfg);
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cfg.g_pin = lcd->d5;
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gpio_pin_set_flags(lcd->handle, &cfg);
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cfg.g_pin = lcd->d6;
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gpio_pin_set_flags(lcd->handle, &cfg);
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cfg.g_pin = lcd->d7;
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gpio_pin_set_flags(lcd->handle, &cfg);
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lcd->is_read = is_read;
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}
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}
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static void lcd_pulse_enable(LCD *lcd) {
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gpio_pin_high(lcd->handle, lcd->en);
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usleep(1); // min of 1000ns
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gpio_pin_low(lcd->handle, lcd->en);
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}
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LCD *lcd_open(gpio_handle_t handle, int rs, int rw, int en, int d0, int d1,
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int d2, int d3, int d4, int d5, int d6, int d7) {
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LCD *lcd = malloc_checked(sizeof(LCD));
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lcd->handle = handle;
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lcd->rs = rs;
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lcd->rw = rw;
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lcd->en = en;
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lcd->d0 = d0;
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lcd->d1 = d1;
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lcd->d2 = d2;
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lcd->d3 = d3;
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lcd->d4 = d4;
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lcd->d5 = d5;
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lcd->d6 = d6;
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lcd->d7 = d7;
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lcd_set_read(lcd, false, true);
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lcd_clear(lcd);
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lcd_call(lcd, 0, 0, 0, 0, 1, 1, 1, 0, 0); // 5x8 font, 2 lines, 8bit
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lcd_entry_mode(lcd, LCD_INCREMENT, LCD_CURSOR_MOVE);
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lcd_display_control(lcd, LCD_CURSOR_NO_BLINK, LCD_CURSOR_OFF, LCD_DISPLAY_ON);
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return lcd;
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}
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void lcd_close(LCD *lcd) {
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free(lcd);
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}
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void lcd_call(LCD *lcd, int rs, int d0, int d1, int d2, int d3, int d4, int d5,
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int d6, int d7) {
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while(lcd_is_busy(lcd)) {
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usleep(5);
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}
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lcd_set_read(lcd, false, false);
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gpio_pin_low(lcd->handle, lcd->en);
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gpio_pin_low(lcd->handle, lcd->rw);
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gpio_pin_set(lcd->handle, lcd->rs, rs);
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gpio_pin_set(lcd->handle, lcd->d0, d0);
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gpio_pin_set(lcd->handle, lcd->d1, d1);
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gpio_pin_set(lcd->handle, lcd->d2, d2);
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gpio_pin_set(lcd->handle, lcd->d3, d3);
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gpio_pin_set(lcd->handle, lcd->d4, d4);
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gpio_pin_set(lcd->handle, lcd->d5, d5);
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gpio_pin_set(lcd->handle, lcd->d6, d6);
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gpio_pin_set(lcd->handle, lcd->d7, d7);
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lcd_pulse_enable(lcd);
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}
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void lcd_write_char(LCD *lcd, char c) {
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lcd_call(lcd, 1, c & 1, (c >> 1) & 1, (c >> 2) & 1, (c >> 3) & 1, (c >> 4) & 1,
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(c >> 5) & 1, (c >> 6) & 1, (c >> 7) & 1);
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}
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size_t lcd_write_string(LCD *lcd, const char *str) {
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size_t count;
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for (count = 0; *str; ++str, ++count) {
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lcd_write_char(lcd, *str);
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}
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return count;
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}
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void lcd_move_to(LCD *lcd, int line, int col) {
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lcd_call(lcd, 0, col & 1, (col >> 1) & 1, (col >> 2) & 1,
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(col >> 3) & 1, (col >> 4) & 1, (col >> 5) & 1, line, 1);
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}
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void lcd_clear(LCD *lcd) {
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lcd_call(lcd, 0, 1, 0, 0, 0, 0, 0, 0, 0);
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}
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void lcd_display_control(LCD *lcd, int b, int c, int d) {
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lcd_call(lcd, 0, b, c, d, 1, 0, 0, 0, 0);
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}
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void lcd_entry_mode(LCD *lcd, int id, int s) {
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lcd_call(lcd, 0, s, id, 1, 0, 0, 0, 0, 0);
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}
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void lcd_cursor_shift(LCD *lcd, int sc, int rl) {
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lcd_call(lcd, 0, 0, 0, rl, sc, 1, 0, 0, 0);
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}
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bool lcd_is_busy(LCD *lcd) {
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lcd_set_read(lcd, true, false);
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gpio_pin_low(lcd->handle, lcd->rs);
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gpio_pin_high(lcd->handle, lcd->rw);
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gpio_pin_high(lcd->handle, lcd->en);
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usleep(1);
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gpio_value_t busy = gpio_pin_get(lcd->handle, lcd->d7);
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gpio_pin_low(lcd->handle, lcd->en);
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usleep(1);
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return busy;
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}
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107
lcd.h
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107
lcd.h
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@ -0,0 +1,107 @@
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/*
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* lcd.h - Subroutines for communicating with HD44780U based LCD panels
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* Copyright (C) 2024 Alexander Rosenberg
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*
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* This program is free software: you can redistribute it and/or modify it under
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* the terms of the GNU General Public License as published by the Free Software
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* Foundation, either version 3 of the License, or (at your option) any later
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* version. See the LICENSE file for more information.
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*/
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#ifndef INCLUDED_LCD_H
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#define INCLUDED_LCD_H
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#include <sys/types.h>
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#include <libgpio.h>
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#include <stdbool.h>
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typedef struct {
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gpio_handle_t handle;
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// pin numbers
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int rs; // register select
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int rw; // read-write
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int en; // enable
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int d0;
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int d1;
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int d2;
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int d3;
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int d4;
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int d5;
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int d6;
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int d7;
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// internal use
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bool is_read;
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} LCD;
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/*
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* Allocate and initialize a new LCD object and return a pointer to it. HANDLE
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* is a gpio_handle_t, each of the other arguments corresponds to the GPIO pin
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* number that the given controller pin is connected to: "register select",
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* "read-write", "enable", and data pins 0-7.
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* Return: the newly created object.
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*/
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LCD *lcd_open(gpio_handle_t handle, int rs, int rw, int en, int d0, int d1,
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int d2, int d3, int d4, int d5, int d6, int d7);
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/*
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* Close LCD by freeing any resources associated with it.
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*/
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void lcd_close(LCD *lcd);
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/*
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* Call a single instruction on LCD. Each argument is the value of that pin.
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*/
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void lcd_call(LCD *lcd, int rs, int d0, int d1, int d2, int d3, int d4, int d5,
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int d6, int d7);
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/*
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* Write character C to LCD.
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*/
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void lcd_write_char(LCD *lcd, char c);
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/*
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* Write STR to LCD.
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* Return: the number of characters written.
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*/
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size_t lcd_write_string(LCD *lcd, const char *str);
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/*
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* Move the cursor to COL on LINE, which both start from 0.
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*/
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void lcd_move_to(LCD *lcd, int line, int col);
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/*
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* Clear LCD and return the cursor to the top right.
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*/
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void lcd_clear(LCD *lcd);
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#define LCD_DISPLAY_ON 1
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#define LCD_DISPLAY_OFF 0
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#define LCD_CURSOR_ON 1
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#define LCD_CURSOR_OFF 0
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#define LCD_CURSOR_BLINK 1
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#define LCD_CURSOR_NO_BLINK 0
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/*
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* Control B, cursor blink, C, cursor visibility, and D, display power for LCD.
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*/
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void lcd_display_control(LCD *lcd, int b, int c, int d);
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#define LCD_INCREMENT 1
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#define LCD_DECREMENT 0
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#define LCD_DISPLAY_SHIFT 1
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#define LCD_CURSOR_MOVE 0
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#define LCD_SHIFT_RIGHT 1
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#define LCD_SHIFT_LEFT 0
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/*
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* Control shift and increment for LCD.
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*/
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void lcd_entry_mode(LCD *lcd, int id, int s);
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/*
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* Control direction and shift/move for cursor for LCD.
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*/
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void lcd_cursor_shift(LCD *lcd, int sc, int rl);
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/*
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* Return: weather the busy flag is set for LCD.
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*/
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bool lcd_is_busy(LCD *lcd);
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#endif
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30
main.c
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30
main.c
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#include "lcd.h"
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#include <unistd.h>
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#include <err.h>
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#define RS 2
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#define RW 3
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#define EN 4
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#define D0 17
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#define D1 27
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#define D2 22
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#define D3 10
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#define D4 9
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#define D5 14
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#define D6 15
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#define D7 18
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int main(int argc, const char **argv) {
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gpio_handle_t handle = gpio_open(0);
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if (handle == GPIO_INVALID_HANDLE) {
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errx(1, "count not open GPIO handle!");
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}
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LCD *lcd = lcd_open(handle, RS, RW, EN, D0, D1, D2, D3, D4, D5, D6, D7);
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lcd_write_string(lcd, "This is a test");
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lcd_move_to(lcd, 1, 0);
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lcd_write_string(lcd, "FreeBSD!");
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lcd_close(lcd);
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gpio_close(handle);
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return 0;
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}
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29
util.c
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29
util.c
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/*
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* util.c - Utility functions
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* Copyright (C) 2024 Alexander Rosenberg
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*
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* This program is free software: you can redistribute it and/or modify it under
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* the terms of the GNU General Public License as published by the Free Software
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* Foundation, either version 3 of the License, or (at your option) any later
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* version. See the LICENSE file for more information.
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*/
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#include "util.h"
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#include <err.h>
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struct GlobalFlags GLOBAL_FLAGS = {
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.config_path = NULL,
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.gpio_path = NULL,
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};
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void *malloc_checked(size_t n) {
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return realloc_checked(NULL, n);
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}
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void *realloc_checked(void *old_ptr, size_t n) {
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void *ptr = realloc(old_ptr, n);
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if (n && !ptr) {
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errx(1, "out of memory!");
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}
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return ptr;
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}
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33
util.h
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33
util.h
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/*
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* util.h - Utility functions
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* Copyright (C) 2024 Alexander Rosenberg
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*
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* This program is free software: you can redistribute it and/or modify it under
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* the terms of the GNU General Public License as published by the Free Software
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* Foundation, either version 3 of the License, or (at your option) any later
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* version. See the LICENSE file for more information.
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*/
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#ifndef INCLUDED_UTIL_H
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#define INCLUDED_UTIL_H
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#include <stdlib.h>
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struct GlobalFlags {
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const char *config_path; // path to config file
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const char *gpio_path; // path of GPIO device file to use
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};
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extern struct GlobalFlags GLOBAL_FLAGS;
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/*
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* Like malloc(3), except that if allocation fails, an error will be written to
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* standard error and abort(3) called
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*/
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void *malloc_checked(size_t n);
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/*
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* Like realloc(3), except that if allocation fails, an error will be written to
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* standard error and abort(3) called
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*/
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void *realloc_checked(void *old_ptr, size_t n);
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#endif
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