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Raspberry Pi Pico internal temperature sensor with LCD 16x2 example.
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/** | |
* | |
* Raspberry Pi Pico internal temperature sensor with LCD 16x2 example. | |
* | |
* Copyright (c) 2020 Raspberry Pi (Trading) Ltd. | |
* | |
* Adapted by MaxMacSTN | |
* | |
* SPDX-License-Identifier: BSD-3-Clause | |
*/ | |
#include <stdio.h> | |
#include <string.h> | |
#include "pico/stdlib.h" | |
#include "hardware/i2c.h" | |
#include "hardware/gpio.h" | |
#include "hardware/adc.h" | |
#include "pico/binary_info.h" | |
#include <math.h> | |
/* Example code to drive a 16x2 LCD panel via a I2C bridge chip (e.g. PCF8574) | |
NOTE: The panel must be capable of being driven at 3.3v NOT 5v. The Pico | |
GPIO (and therefor I2C) cannot be used at 5v. | |
You will need to use a level shifter on the I2C lines if you want to run the | |
board at 5v. | |
Connections on Raspberry Pi Pico board, other boards may vary. | |
GPIO 4 (pin 6)-> SDA on LCD bridge board | |
GPIO 5 (pin 7)-> SCL on LCD bridge board | |
3.3v (pin 36) -> VCC on LCD bridge board | |
GND (pin 38) -> GND on LCD bridge board | |
*/ | |
// commands | |
const int LCD_CLEARDISPLAY = 0x01; | |
const int LCD_RETURNHOME = 0x02; | |
const int LCD_ENTRYMODESET = 0x04; | |
const int LCD_DISPLAYCONTROL = 0x08; | |
const int LCD_CURSORSHIFT = 0x10; | |
const int LCD_FUNCTIONSET = 0x20; | |
const int LCD_SETCGRAMADDR = 0x40; | |
const int LCD_SETDDRAMADDR = 0x80; | |
// flags for display entry mode | |
const int LCD_ENTRYSHIFTINCREMENT = 0x01; | |
const int LCD_ENTRYLEFT = 0x02; | |
// flags for display and cursor control | |
const int LCD_BLINKON = 0x01; | |
const int LCD_CURSORON = 0x02; | |
const int LCD_DISPLAYON = 0x04; | |
// flags for display and cursor shift | |
const int LCD_MOVERIGHT = 0x04; | |
const int LCD_DISPLAYMOVE = 0x08; | |
// flags for function set | |
const int LCD_5x10DOTS = 0x04; | |
const int LCD_2LINE = 0x08; | |
const int LCD_8BITMODE = 0x10; | |
// flag for backlight control | |
const int LCD_BACKLIGHT = 0x08; | |
const int LCD_ENABLE_BIT = 0x04; | |
#define I2C_PORT i2c0 | |
// By default these LCD display drivers are on bus address 0x27 | |
static int addr = 0x27; | |
// Modes for lcd_send_byte | |
#define LCD_CHARACTER 1 | |
#define LCD_COMMAND 0 | |
#define MAX_LINES 2 | |
#define MAX_CHARS 16 | |
const uint LED_PIN = PICO_DEFAULT_LED_PIN; | |
const uint DHT_PIN = 15; | |
const uint MAX_TIMINGS = 85; | |
/* Quick helper function for single byte transfers */ | |
void i2c_write_byte(uint8_t val) { | |
i2c_write_blocking(I2C_PORT, addr, &val, 1, false); | |
} | |
void lcd_toggle_enable(uint8_t val) { | |
// Toggle enable pin on LCD display | |
// We cannot do this too quickly or things don't work | |
#define DELAY_US 600 | |
sleep_us(DELAY_US); | |
i2c_write_byte(val | LCD_ENABLE_BIT); | |
sleep_us(DELAY_US); | |
i2c_write_byte(val & ~LCD_ENABLE_BIT); | |
sleep_us(DELAY_US); | |
} | |
// The display is sent a byte as two separate nibble transfers | |
void lcd_send_byte(uint8_t val, int mode) { | |
uint8_t high = mode | (val & 0xF0) | LCD_BACKLIGHT; | |
uint8_t low = mode | ((val << 4) & 0xF0) | LCD_BACKLIGHT; | |
i2c_write_byte(high); | |
lcd_toggle_enable(high); | |
i2c_write_byte(low); | |
lcd_toggle_enable(low); | |
} | |
void lcd_clear(void) { | |
lcd_send_byte(LCD_CLEARDISPLAY, LCD_COMMAND); | |
} | |
// go to location on LCD | |
void lcd_set_cursor(int line, int position) { | |
int val = (line == 0) ? 0x80 + position : 0xC0 + position; | |
lcd_send_byte(val, LCD_COMMAND); | |
} | |
static void inline lcd_char(char val) { | |
lcd_send_byte(val, LCD_CHARACTER); | |
} | |
void lcd_string(const char *s) { | |
while (*s) { | |
lcd_char(*s++); | |
} | |
} | |
void lcd_init() { | |
lcd_send_byte(0x03, LCD_COMMAND); | |
lcd_send_byte(0x03, LCD_COMMAND); | |
lcd_send_byte(0x03, LCD_COMMAND); | |
lcd_send_byte(0x02, LCD_COMMAND); | |
lcd_send_byte(LCD_ENTRYMODESET | LCD_ENTRYLEFT, LCD_COMMAND); | |
lcd_send_byte(LCD_FUNCTIONSET | LCD_2LINE, LCD_COMMAND); | |
lcd_send_byte(LCD_DISPLAYCONTROL | LCD_DISPLAYON, LCD_COMMAND); | |
lcd_clear(); | |
} | |
int main() { | |
stdio_init_all(); | |
adc_init(); | |
// Select ADC input 0 (GPIO26) | |
gpio_set_dir(LED_PIN, GPIO_OUT); | |
// This example will use I2C0 on GPIO4 (SDA) and GPIO5 (SCL) | |
i2c_init(I2C_PORT, 100 * 1000); | |
gpio_set_function(4, GPIO_FUNC_I2C); | |
gpio_set_function(5, GPIO_FUNC_I2C); | |
gpio_pull_up(4); | |
gpio_pull_up(5); | |
// Make the I2C pins available to picotool | |
bi_decl( bi_2pins_with_func(4, 5, GPIO_FUNC_I2C)); | |
lcd_init(); | |
while (1) { | |
const float conversion_factor = 3.3f / (1 << 12); | |
adc_select_input(4); | |
uint16_t result = adc_read(); | |
printf("Raw value: 0x%03x, voltage: %f V\n", result, result * conversion_factor); | |
float reading = result * conversion_factor; | |
float tempF = 27 - (reading - 0.706)/0.001721; | |
float tempC = (tempF - 32) * 5/9; | |
char *message[16]; | |
lcd_set_cursor(0, 0); | |
lcd_string(" - RPi Pico - "); | |
lcd_set_cursor(1, 0); | |
sprintf(message, " Temp: %.1fc ",tempC); | |
lcd_string(message); | |
sleep_ms(2000); | |
} | |
return 0; | |
} |
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