mirror of
https://github.com/mytechnotalent/Embedded-Hacking.git
synced 2026-04-01 09:00:18 +02:00
115 lines
3.1 KiB
C
115 lines
3.1 KiB
C
/**
|
|
* @file lcd_1602.c
|
|
* @brief Implementation of PCF8574-backed HD44780 (16x2) LCD driver
|
|
* @author Kevin Thomas
|
|
* @date 2025
|
|
*
|
|
* MIT License
|
|
*
|
|
* Copyright (c) 2025 Kevin Thomas
|
|
*
|
|
* Permission is hereby granted, free of charge, to any person obtaining a copy
|
|
* of this software and associated documentation files (the "Software"), to deal
|
|
* in the Software without restriction, including without limitation the rights
|
|
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
|
|
* copies of the Software, and to permit persons to whom the Software is
|
|
* furnished to do so, subject to the following conditions:
|
|
*
|
|
* The above copyright notice and this permission notice shall be included in all
|
|
* copies or substantial portions of the Software.
|
|
*
|
|
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
|
|
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
|
|
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
|
|
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
|
|
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
|
|
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
|
|
* SOFTWARE.
|
|
*/
|
|
|
|
#include "lcd_1602.h"
|
|
#include <string.h>
|
|
#include <stdint.h>
|
|
|
|
static i2c_inst_t *lcd_i2c = NULL;
|
|
static uint8_t lcd_addr = 0x27;
|
|
static int lcd_nibble_shift = 4;
|
|
static uint8_t lcd_backlight_mask = 0x08;
|
|
|
|
/* PCF8574 -> LCD control pins */
|
|
#define PIN_RS 0x01
|
|
#define PIN_RW 0x02
|
|
#define PIN_EN 0x04
|
|
|
|
static void pcf_write_byte(uint8_t data) {
|
|
if (!lcd_i2c) return;
|
|
i2c_write_blocking(lcd_i2c, lcd_addr, &data, 1, false);
|
|
}
|
|
|
|
static void pcf_pulse_enable(uint8_t data) {
|
|
pcf_write_byte(data | PIN_EN);
|
|
sleep_us(1);
|
|
pcf_write_byte(data & ~PIN_EN);
|
|
sleep_us(50);
|
|
}
|
|
|
|
static void lcd_write4(uint8_t nibble, uint8_t mode) {
|
|
uint8_t data = (nibble & 0x0F) << lcd_nibble_shift;
|
|
data |= mode ? PIN_RS : 0;
|
|
data |= lcd_backlight_mask;
|
|
pcf_pulse_enable(data);
|
|
}
|
|
|
|
static void lcd_send(uint8_t value, uint8_t mode) {
|
|
lcd_write4((value >> 4) & 0x0F, mode);
|
|
lcd_write4(value & 0x0F, mode);
|
|
}
|
|
|
|
void lcd_i2c_init(i2c_inst_t *i2c, uint8_t pcf_addr, int nibble_shift, uint8_t backlight_mask) {
|
|
lcd_i2c = i2c;
|
|
lcd_addr = pcf_addr;
|
|
lcd_nibble_shift = nibble_shift;
|
|
lcd_backlight_mask = backlight_mask;
|
|
|
|
// Follow init sequence for HD44780 in 4-bit mode
|
|
lcd_write4(0x03, 0);
|
|
sleep_ms(5);
|
|
lcd_write4(0x03, 0);
|
|
sleep_us(150);
|
|
lcd_write4(0x03, 0);
|
|
sleep_us(150);
|
|
lcd_write4(0x02, 0);
|
|
sleep_us(150);
|
|
|
|
// Function set: 4-bit, 2 lines
|
|
lcd_send(0x28, 0);
|
|
|
|
// Display on, cursor off
|
|
lcd_send(0x0C, 0);
|
|
|
|
// Clear
|
|
lcd_send(0x01, 0);
|
|
sleep_ms(2);
|
|
|
|
// Entry mode set
|
|
lcd_send(0x06, 0);
|
|
}
|
|
|
|
void lcd_clear(void) {
|
|
lcd_send(0x01, 0);
|
|
sleep_ms(2);
|
|
}
|
|
|
|
void lcd_set_cursor(int line, int position) {
|
|
const uint8_t row_offsets[] = {0x00, 0x40};
|
|
|
|
if (line > 1) line = 1;
|
|
lcd_send(0x80 | (position + row_offsets[line]), 0);
|
|
}
|
|
|
|
void lcd_puts(const char *s) {
|
|
while (*s) {
|
|
lcd_send((uint8_t)*s++, 1);
|
|
}
|
|
}
|