I2C LCD with ESP32 using ESP-IDF
main.c
#include <stdio.h>
#include "driver/i2c.h"
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "sdkconfig.h"
#include "HD44780.h"
#define LCD_ADDR 0x27
// *** 修正: 確保這裡只有標準空格 ***
#define SDA_PIN 21
#define SCL_PIN 22
// ********************************
#define LCD_COLS 16
#define LCD_ROWS 2
void LCD_DemoTask(void* param)
{
char num[20];
while (true) {
LCD_home();
LCD_clearScreen();
LCD_writeStr("16x2 I2C LCD");
// *** 修正: 替換為 portTICK_PERIOD_MS ***
vTaskDelay(3000 / portTICK_PERIOD_MS);
LCD_clearScreen();
LCD_writeStr("Lets Count 0-10!");
// *** 修正: 替換為 portTICK_PERIOD_MS ***
vTaskDelay(3000 / portTICK_PERIOD_MS);
LCD_clearScreen();
for (int i = 0; i <= 10; i++) {
// 游標設定在 (col, row)。假設 row 從 0 開始，1 為第二行
LCD_setCursor(7, 1);
sprintf(num, "%2d", i);
LCD_writeStr(num);
// *** 修正: 替換為 portTICK_PERIOD_MS ***
vTaskDelay(1000 / portTICK_PERIOD_MS);
}
// 額外的延遲，讓計數結果顯示得久一點
vTaskDelay(3000 / portTICK_PERIOD_MS);
}
}
void app_main(void)
{
LCD_init(LCD_ADDR, SDA_PIN, SCL_PIN, LCD_COLS, LCD_ROWS);
// 增加堆疊大小以提供更多的安全空間 (2048 * 2)
xTaskCreate(&LCD_DemoTask, "Demo Task", 4096, NULL, 5, NULL);
}
hd44780.h
#pragma once
#include <stdint.h>
void LCD_init(uint8_t addr, uint8_t dataPin, uint8_t clockPin, uint8_t cols, uint8_t rows);
void LCD_setCursor(uint8_t col, uint8_t row);
void LCD_home(void);
void LCD_clearScreen(void);
void LCD_writeChar(char c);
void LCD_writeStr(char* str);
hd44780.c
#include <driver/i2c.h>
#include <esp_log.h>
#include <freertos/FreeRTOS.h>
#include <freertos/task.h>
#include <stdio.h>
#include "sdkconfig.h"
#include "rom/ets_sys.h"
#include <esp_log.h>
// LCD module defines
#define LCD_LINEONE 0x00 // start of line 1
#define LCD_LINETWO 0x40 // start of line 2
#define LCD_LINETHREE 0x14 // start of line 3
#define LCD_LINEFOUR 0x54 // start of line 4
#define LCD_BACKLIGHT 0x08
#define LCD_ENABLE 0x04
#define LCD_COMMAND 0x00
#define LCD_WRITE 0x01
#define LCD_SET_DDRAM_ADDR 0x80
#define LCD_READ_BF 0x40
// LCD instructions
#define LCD_CLEAR 0x01 // replace all characters with ASCII 'space'
#define LCD_HOME 0x02 // return cursor to first position on first line
#define LCD_ENTRY_MODE 0x06 // shift cursor from left to right on read/write
#define LCD_DISPLAY_OFF 0x08 // turn display off
#define LCD_DISPLAY_ON 0x0C // display on, cursor off, don't blink character
#define LCD_FUNCTION_RESET 0x30 // reset the LCD
#define LCD_FUNCTION_SET_4BIT 0x28 // 4-bit data, 2-line display, 5 x 7 font
#define LCD_SET_CURSOR 0x80 // set cursor position
// Pin mappings
// P0 -> RS
// P1 -> RW
// P2 -> E
// P3 -> Backlight
// P4 -> D4
// P5 -> D5
// P6 -> D6
// P7 -> D7
static char tag[] = "LCD Driver";
static uint8_t LCD_addr;
static uint8_t SDA_pin;
static uint8_t SCL_pin;
static uint8_t LCD_cols;
static uint8_t LCD_rows;
static void LCD_writeNibble(uint8_t nibble, uint8_t mode);
static void LCD_writeByte(uint8_t data, uint8_t mode);
static void LCD_pulseEnable(uint8_t nibble);
static esp_err_t I2C_init(void)
{
i2c_config_t conf = {
.mode = I2C_MODE_MASTER,
.sda_io_num = SDA_pin,
.scl_io_num = SCL_pin,
.sda_pullup_en = GPIO_PULLUP_ENABLE,
.scl_pullup_en = GPIO_PULLUP_ENABLE,
.master.clk_speed = 100000
};
i2c_param_config(I2C_NUM_0, &conf);
i2c_driver_install(I2C_NUM_0, I2C_MODE_MASTER, 0, 0, 0);
return ESP_OK;
}
void LCD_init(uint8_t addr, uint8_t dataPin, uint8_t clockPin, uint8_t cols, uint8_t rows)
{
LCD_addr = addr;
SDA_pin = dataPin;
SCL_pin = clockPin;
LCD_cols = cols;
LCD_rows = rows;
I2C_init();
vTaskDelay(100 / portTICK_PERIOD_MS); // Initial 40 mSec delay
// Reset the LCD controller
LCD_writeNibble(LCD_FUNCTION_RESET, LCD_COMMAND); // First part of reset sequence
vTaskDelay(10 / portTICK_PERIOD_MS); // 4.1 mS delay (min)
LCD_writeNibble(LCD_FUNCTION_RESET, LCD_COMMAND); // second part of reset sequence
ets_delay_us(200); // 100 uS delay (min)
LCD_writeNibble(LCD_FUNCTION_RESET, LCD_COMMAND); // Third time's a charm
LCD_writeNibble(LCD_FUNCTION_SET_4BIT, LCD_COMMAND); // Activate 4-bit mode
ets_delay_us(80); // 40 uS delay (min)
// --- Busy flag now available ---
// Function Set instruction
LCD_writeByte(LCD_FUNCTION_SET_4BIT, LCD_COMMAND); // Set mode, lines, and font
ets_delay_us(80);
// Clear Display instruction
LCD_writeByte(LCD_CLEAR, LCD_COMMAND); // clear display RAM
vTaskDelay(2 / portTICK_PERIOD_MS); // Clearing memory takes a bit longer
// Entry Mode Set instruction
LCD_writeByte(LCD_ENTRY_MODE, LCD_COMMAND); // Set desired shift characteristics
ets_delay_us(80);
LCD_writeByte(LCD_DISPLAY_ON, LCD_COMMAND); // Ensure LCD is set to on
}
void LCD_setCursor(uint8_t col, uint8_t row)
{
if (row > LCD_rows - 1) {
ESP_LOGE(tag, "Cannot write to row %d. Please select a row in the range (0, %d)", row, LCD_rows-1);
row = LCD_rows - 1;
}
uint8_t row_offsets[] = {LCD_LINEONE, LCD_LINETWO, LCD_LINETHREE, LCD_LINEFOUR};
LCD_writeByte(LCD_SET_DDRAM_ADDR | (col + row_offsets[row]), LCD_COMMAND);
}
void LCD_writeChar(char c)
{
LCD_writeByte(c, LCD_WRITE); // Write data to DDRAM
}
void LCD_writeStr(char* str)
{
while (*str) {
LCD_writeChar(*str++);
}
}
void LCD_home(void)
{
LCD_writeByte(LCD_HOME, LCD_COMMAND);
vTaskDelay(2 / portTICK_PERIOD_MS); // This command takes a while to complete
}
void LCD_clearScreen(void)
{
LCD_writeByte(LCD_CLEAR, LCD_COMMAND);
vTaskDelay(2 / portTICK_PERIOD_MS); // This command takes a while to complete
}
static void LCD_writeNibble(uint8_t nibble, uint8_t mode)
{
uint8_t data = (nibble & 0xF0) | mode | LCD_BACKLIGHT;
i2c_cmd_handle_t cmd = i2c_cmd_link_create();
ESP_ERROR_CHECK(i2c_master_start(cmd));
ESP_ERROR_CHECK(i2c_master_write_byte(cmd, (LCD_addr << 1) | I2C_MASTER_WRITE, 1));
ESP_ERROR_CHECK(i2c_master_write_byte(cmd, data, 1));
ESP_ERROR_CHECK(i2c_master_stop(cmd));
ESP_ERROR_CHECK(i2c_master_cmd_begin(I2C_NUM_0, cmd, 1000/portTICK_PERIOD_MS));
i2c_cmd_link_delete(cmd);
LCD_pulseEnable(data); // Clock data into LCD
}
static void LCD_writeByte(uint8_t data, uint8_t mode)
{
LCD_writeNibble(data & 0xF0, mode);
LCD_writeNibble((data << 4) & 0xF0, mode);
}
static void LCD_pulseEnable(uint8_t data)
{
i2c_cmd_handle_t cmd = i2c_cmd_link_create();
ESP_ERROR_CHECK(i2c_master_start(cmd));
ESP_ERROR_CHECK(i2c_master_write_byte(cmd, (LCD_addr << 1) | I2C_MASTER_WRITE, 1));
ESP_ERROR_CHECK(i2c_master_write_byte(cmd, data | LCD_ENABLE, 1));
ESP_ERROR_CHECK(i2c_master_stop(cmd));
ESP_ERROR_CHECK(i2c_master_cmd_begin(I2C_NUM_0, cmd, 1000/portTICK_PERIOD_MS));
i2c_cmd_link_delete(cmd);
ets_delay_us(1);
cmd = i2c_cmd_link_create();
ESP_ERROR_CHECK(i2c_master_start(cmd));
ESP_ERROR_CHECK(i2c_master_write_byte(cmd, (LCD_addr << 1) | I2C_MASTER_WRITE, 1));
ESP_ERROR_CHECK(i2c_master_write_byte(cmd, (data & ~LCD_ENABLE), 1));
ESP_ERROR_CHECK(i2c_master_stop(cmd));
ESP_ERROR_CHECK(i2c_master_cmd_begin(I2C_NUM_0, cmd, 1000/portTICK_PERIOD_MS));
i2c_cmd_link_delete(cmd);
ets_delay_us(500);
}
diagram.json
{
"version": 1,
"author": "alex wu",
"editor": "wokwi",
"parts": [
{
"type": "board-esp32-devkit-c-v4",
"id": "esp",
"top": -153.6,
"left": -167.96,
"attrs": { "builder": "esp-idf" }
},
{ "type": "wokwi-lcd1602", "id": "lcd1", "top": -128, "left": -4, "attrs": { "pins": "i2c" } }
],
"connections": [
[ "esp:TX", "$serialMonitor:RX", "", [] ],
[ "esp:RX", "$serialMonitor:TX", "", [] ],
[ "esp:21", "lcd1:SDA", "green", [ "h48", "v-28.8" ] ],
[
"esp:22",
"lcd1:SCL",
"green",
[ "h19.2", "v-57.6", "h-134.4", "v240", "h144", "v-144", "h-9.6" ]
],
[ "esp:3V3", "lcd1:VCC", "red", [ "h0.15", "v-48", "h144", "v86.4" ] ],
[ "esp:GND.2", "lcd1:GND", "black", [ "v0", "h57.6", "v28.8" ] ]
],
"dependencies": {}
}
