Overview
In this article, we will make Fire Alarm System using Flame Sensor & Raspberry Pi Pico. A flame Sensor can be used to detect fire sources or other light sources of the wavelength in the range of 760nm – 1100 nm. It is based on the YG1006 sensor which is a high-speed and highly sensitive NPN silicon phototransistor.
In this project we interface Flame Sensor with Arduino and learn all the steps to build Fire Alarm System by using Raspberry Pi Pico and a flame sensor. The flame sensor module has a photodiode to detect the light and an op-amp to control the sensitivity. It is used to detect fire and provide a HIGH signal upon detection. Raspberry Pi Pico reads the signal and provides an alert by turning on the RGB LED & also by displaying a message on a 16×2 LCD Display.
Components Required
In this guide, I used Elecrow Raspberry Pi Pico Starter Kit to test different Modules. You can buy the kit and perform some other operations as well. From this kit, you can use the following components.
1. Raspberry Pi Pico Board – 1
2. 16×2 I2C LCD Display – 1
3. Flame Sensor – 1
4. Breadboard – 1
5. RGB LED Module – 1
6. Jumper Wires – 10
7. Micro-USB Cable – 1
Flame Sensor
This flame sensor or fire sensor module works on the concept that when a flame or fire is burning it emits IR signals. This IR signal is then received by the IR receiver on the fire sensor module to detect the flame or fire.
The sensor has an operating voltage from 3V to 5.5V and has both digital and analog output. The sensitivity of the digital output can be controlled by the onboard potentiometer. The detection angle of the sensor is 60 degrees and the range is theoretically 100cm but practically you can get up to 20-30cm.
The flame sensor is generally divided into far-infrared flame sensors and ultraviolet flame sensors, and their working principle is to detect the heat radiation of a fire source of a specific wavelength. The far-infrared flame sensor can detect infrared light with a wavelength in the range of 700 nanometers to 1000 nanometers.
When the infrared light wavelength is around 880 nanometers, its sensitivity reaches the maximum. The far-infrared flame probe converts the change in the intensity of the external infrared light into the change of the current, which is reflected as the change of the value in the range of 0~65535 through the A/D converter.
Fire Alarm System using Flame Sensor & Raspberry Pi Pico
The schematic for the Fire Alarm System using a Flame Sensor, Raspberry Pi Pico & LCD Display is given below.
Connect the LCD VCC & GND Pin to Raspberry Pi Pico 5V & GND Pin respectively. Connect the SDA & SCL pins of the LCD to Raspberry Pi Pico GP0 & GP1 pins respectively.
The VCC, GND & analog output pin of the Flame Sensor is connected to the VSYS, GND & GP26 of Raspberry Pi Pico. There is an RGB LED used for indication. The RGB LED R, G, and B pins are connected to the GP4, GP3, and GP2 pins of Raspberry Pi Pico.
MicroPython Code/Program
The code is divided into 3 parts. The 1st one is i2c_lcd.py, the 2nd one is lcd_api.py & 3rd one is main.py. The LCD doesn’t work directly as it requires few libraries.
lcd_api.py
Copy the following code and save it as lcd_api.py in Raspberry Pi Pico.
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"""Provides an API for talking to HD44780 compatible character LCDs.""" import time class LcdApi: """Implements the API for talking with HD44780 compatible character LCDs. This class only knows what commands to send to the LCD, and not how to get them to the LCD. It is expected that a derived class will implement the hal_xxx functions. """ # The following constant names were lifted from the avrlib lcd.h # header file, however, I changed the definitions from bit numbers # to bit masks. # # HD44780 LCD controller command set LCD_CLR = 0x01 # DB0: clear display LCD_HOME = 0x02 # DB1: return to home position LCD_ENTRY_MODE = 0x04 # DB2: set entry mode LCD_ENTRY_INC = 0x02 # --DB1: increment LCD_ENTRY_SHIFT = 0x01 # --DB0: shift LCD_ON_CTRL = 0x08 # DB3: turn lcd/cursor on LCD_ON_DISPLAY = 0x04 # --DB2: turn display on LCD_ON_CURSOR = 0x02 # --DB1: turn cursor on LCD_ON_BLINK = 0x01 # --DB0: blinking cursor LCD_MOVE = 0x10 # DB4: move cursor/display LCD_MOVE_DISP = 0x08 # --DB3: move display (0-> move cursor) LCD_MOVE_RIGHT = 0x04 # --DB2: move right (0-> left) LCD_FUNCTION = 0x20 # DB5: function set LCD_FUNCTION_8BIT = 0x10 # --DB4: set 8BIT mode (0->4BIT mode) LCD_FUNCTION_2LINES = 0x08 # --DB3: two lines (0->one line) LCD_FUNCTION_10DOTS = 0x04 # --DB2: 5x10 font (0->5x7 font) LCD_FUNCTION_RESET = 0x30 # See "Initializing by Instruction" section LCD_CGRAM = 0x40 # DB6: set CG RAM address LCD_DDRAM = 0x80 # DB7: set DD RAM address LCD_RS_CMD = 0 LCD_RS_DATA = 1 LCD_RW_WRITE = 0 LCD_RW_READ = 1 def __init__(self, num_lines, num_columns): self.num_lines = num_lines if self.num_lines > 4: self.num_lines = 4 self.num_columns = num_columns if self.num_columns > 40: self.num_columns = 40 self.cursor_x = 0 self.cursor_y = 0 self.backlight = True self.display_off() self.backlight_on() self.clear() self.hal_write_command(self.LCD_ENTRY_MODE | self.LCD_ENTRY_INC) self.hide_cursor() self.display_on() def clear(self): """Clears the LCD display and moves the cursor to the top left corner. """ self.hal_write_command(self.LCD_CLR) self.hal_write_command(self.LCD_HOME) self.cursor_x = 0 self.cursor_y = 0 def show_cursor(self): """Causes the cursor to be made visible.""" self.hal_write_command(self.LCD_ON_CTRL | self.LCD_ON_DISPLAY | self.LCD_ON_CURSOR) def hide_cursor(self): """Causes the cursor to be hidden.""" self.hal_write_command(self.LCD_ON_CTRL | self.LCD_ON_DISPLAY) def blink_cursor_on(self): """Turns on the cursor, and makes it blink.""" self.hal_write_command(self.LCD_ON_CTRL | self.LCD_ON_DISPLAY | self.LCD_ON_CURSOR | self.LCD_ON_BLINK) def blink_cursor_off(self): """Turns on the cursor, and makes it no blink (i.e. be solid).""" self.hal_write_command(self.LCD_ON_CTRL | self.LCD_ON_DISPLAY | self.LCD_ON_CURSOR) def display_on(self): """Turns on (i.e. unblanks) the LCD.""" self.hal_write_command(self.LCD_ON_CTRL | self.LCD_ON_DISPLAY) def display_off(self): """Turns off (i.e. blanks) the LCD.""" self.hal_write_command(self.LCD_ON_CTRL) def backlight_on(self): """Turns the backlight on. This isn't really an LCD command, but some modules have backlight controls, so this allows the hal to pass through the command. """ self.backlight = True self.hal_backlight_on() def backlight_off(self): """Turns the backlight off. This isn't really an LCD command, but some modules have backlight controls, so this allows the hal to pass through the command. """ self.backlight = False self.hal_backlight_off() def move_to(self, cursor_x, cursor_y): """Moves the cursor position to the indicated position. The cursor position is zero based (i.e. cursor_x == 0 indicates first column). """ self.cursor_x = cursor_x self.cursor_y = cursor_y addr = cursor_x & 0x3f if cursor_y & 1: addr += 0x40 # Lines 1 & 3 add 0x40 if cursor_y & 2: addr += 0x14 # Lines 2 & 3 add 0x14 self.hal_write_command(self.LCD_DDRAM | addr) def putchar(self, char): """Writes the indicated character to the LCD at the current cursor position, and advances the cursor by one position. """ if char != '\n': self.hal_write_data(ord(char)) self.cursor_x += 1 if self.cursor_x >= self.num_columns or char == '\n': self.cursor_x = 0 self.cursor_y += 1 if self.cursor_y >= self.num_lines: self.cursor_y = 0 self.move_to(self.cursor_x, self.cursor_y) def putstr(self, string): """Write the indicated string to the LCD at the current cursor position and advances the cursor position appropriately. """ for char in string: self.putchar(char) def custom_char(self, location, charmap): """Write a character to one of the 8 CGRAM locations, available as chr(0) through chr(7). """ location &= 0x7 self.hal_write_command(self.LCD_CGRAM | (location << 3)) time.sleep_us(40) for i in range(8): self.hal_write_data(charmap[i]) time.sleep_us(40) self.move_to(self.cursor_x, self.cursor_y) def hal_backlight_on(self): """Allows the hal layer to turn the backlight on. If desired, a derived HAL class will implement this function. """ pass def hal_backlight_off(self): """Allows the hal layer to turn the backlight off. If desired, a derived HAL class will implement this function. """ pass def hal_write_command(self, cmd): """Write a command to the LCD. It is expected that a derived HAL class will implement this function. """ raise NotImplementedError def hal_write_data(self, data): """Write data to the LCD. It is expected that a derived HAL class will implement this function. """ raise NotImplementedError |
i2c_lcd.py
Copy the following code and save it as i2c_lcd.py in Raspberry Pi Pico.
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from lcd_api import LcdApi from machine import I2C from time import sleep_ms # The PCF8574 has a jumper selectable address: 0x20 - 0x27 DEFAULT_I2C_ADDR = 0x27 # Defines shifts or masks for the various LCD line attached to the PCF8574 MASK_RS = 0x01 MASK_RW = 0x02 MASK_E = 0x04 SHIFT_BACKLIGHT = 3 SHIFT_DATA = 4 class I2cLcd(LcdApi): """Implements a HD44780 character LCD connected via PCF8574 on I2C.""" def __init__(self, i2c, i2c_addr, num_lines, num_columns): self.i2c = i2c self.i2c_addr = i2c_addr self.i2c.writeto(self.i2c_addr, bytearray([0])) sleep_ms(20) # Allow LCD time to powerup # Send reset 3 times self.hal_write_init_nibble(self.LCD_FUNCTION_RESET) sleep_ms(5) # need to delay at least 4.1 msec self.hal_write_init_nibble(self.LCD_FUNCTION_RESET) sleep_ms(1) self.hal_write_init_nibble(self.LCD_FUNCTION_RESET) sleep_ms(1) # Put LCD into 4 bit mode self.hal_write_init_nibble(self.LCD_FUNCTION) sleep_ms(1) LcdApi.__init__(self, num_lines, num_columns) cmd = self.LCD_FUNCTION if num_lines > 1: cmd |= self.LCD_FUNCTION_2LINES self.hal_write_command(cmd) def hal_write_init_nibble(self, nibble): """Writes an initialization nibble to the LCD. This particular function is only used during initialization. """ byte = ((nibble >> 4) & 0x0f) << SHIFT_DATA self.i2c.writeto(self.i2c_addr, bytearray([byte | MASK_E])) self.i2c.writeto(self.i2c_addr, bytearray([byte])) def hal_backlight_on(self): """Allows the hal layer to turn the backlight on.""" self.i2c.writeto(self.i2c_addr, bytearray([1 << SHIFT_BACKLIGHT])) def hal_backlight_off(self): """Allows the hal layer to turn the backlight off.""" self.i2c.writeto(self.i2c_addr, bytearray([0])) def hal_write_command(self, cmd): """Writes a command to the LCD. Data is latched on the falling edge of E. """ byte = ((self.backlight << SHIFT_BACKLIGHT) | (((cmd >> 4) & 0x0f) << SHIFT_DATA)) self.i2c.writeto(self.i2c_addr, bytearray([byte | MASK_E])) self.i2c.writeto(self.i2c_addr, bytearray([byte])) byte = ((self.backlight << SHIFT_BACKLIGHT) | ((cmd & 0x0f) << SHIFT_DATA)) self.i2c.writeto(self.i2c_addr, bytearray([byte | MASK_E])) self.i2c.writeto(self.i2c_addr, bytearray([byte])) if cmd <= 3: # The home and clear commands require a worst case delay of 4.1 msec sleep_ms(5) def hal_write_data(self, data): """Write data to the LCD.""" byte = (MASK_RS | (self.backlight << SHIFT_BACKLIGHT) | (((data >> 4) & 0x0f) << SHIFT_DATA)) self.i2c.writeto(self.i2c_addr, bytearray([byte | MASK_E])) self.i2c.writeto(self.i2c_addr, bytearray([byte])) byte = (MASK_RS | (self.backlight << SHIFT_BACKLIGHT) | ((data & 0x0f) << SHIFT_DATA)) self.i2c.writeto(self.i2c_addr, bytearray([byte | MASK_E])) self.i2c.writeto(self.i2c_addr, bytearray([byte])) |
main.py
Copy the following code and save it as main.py in Raspberry Pi Pico.
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from machine import Pin,ADC,PWM,I2C from i2c_lcd import I2cLcd from time import sleep DEFAULT_I2C_ADDR = 0x27 # LCD 1602 I2C address Flame_AO = ADC(0) # ADC0 multiplexing pin is GP26 Led_R = PWM(Pin(4)) Led_G = PWM(Pin(3)) Led_B = PWM(Pin(2)) Led_R.freq(2000) # Set the frequency to 2KHz Led_G.freq(2000) Led_B.freq(2000) i2c = I2C(0,sda=Pin(0),scl=Pin(1),freq=400000) lcd = I2cLcd(i2c, DEFAULT_I2C_ADDR, 2, 16) # Initialize(device address, cursor settings) if __name__ == '__main__': while True: text = 'Warning!\nBe On Fire!' # show alert information Flame_value = Flame_AO.read_u16() # Get the analog value of the flame sensor if Flame_value < 30000: lcd.putstr(text) Led_R.duty_u16(65535) Led_G.duty_u16(0) Led_B.duty_u16(0) sleep(0.5) lcd.clear() Led_R.duty_u16(0) Led_G.duty_u16(0) Led_B.duty_u16(65535) sleep(0.5) else: Led_R.duty_u16(0) Led_G.duty_u16(65535) Led_B.duty_u16(0) |
Now click on the Run button to run all the libraries and the main files.
When a fire source is introduced near the flame sensor, the Fire Alam gets activated. At the same time, RGB LED starts flashing and LCD will display the warning message.
