Project 8: LCD1602 Display

Description

As we all know, screen is one of the best ways for people to interact with electronic devices.

Component Knowledge

1602 is a line that can display 16 characters. There are two lines, which use IIC communication protocol.

Control Pins

SDA	SDA
SCL	SCL

Project 8.1 LCD 1602 Display Characters

Description

We will use library file i2c_lcd.py and lcd_api.py, which should be saved in the ESP32 memory.

Operations

Open“Thonny”，click“This computer”→“D:”→“2. Python Projects”→“pj8_1_lcd1602”. Select “i2c_lcd.py”, right-click your mouse to select “\ Upload to /\ ”，wait for “i2c_lcd.py” to be uploaded to ESP32; and then select “lcd_api.py”, right-click your mouse to select “\ Upload to /\ ”，wait for “lcd_api.py” to be uploaded to ESP32.

The saved name are i2c_lcd.py and lcd_api.py

Test Code

from time import sleep_ms, ticks_ms
from machine import I2C, Pin
from i2c_lcd import I2cLcd

DEFAULT_I2C_ADDR = 0x27

i2c = I2C(scl=Pin(22), sda=Pin(21), freq=400000)
lcd = I2cLcd(i2c, DEFAULT_I2C_ADDR, 2, 16)

lcd.move_to(1, 0)
lcd.putstr('Hello')
lcd.move_to(1, 1)
lcd.putstr('keyestudio')

# The following line of code should be tested
# using the REPL:

# 1. To print a string to the LCD:
#    lcd.putstr('Hello world')
# 2. To clear the display:
#lcd.clear()
# 3. To control the cursor position:
# lcd.move_to(2, 1)
# 4. To show the cursor:
# lcd.show_cursor()
# 5. To hide the cursor:
#lcd.hide_cursor()
# 6. To set the cursor to blink:
#lcd.blink_cursor_on()
# 7. To stop the cursor on blinking:
#lcd.blink_cursor_off()
# 8. To hide the currently displayed character:
#lcd.display_off()
# 9. To show the currently hidden character:
#lcd.display_on()
# 10. To turn off the backlight:
#lcd.backlight_off()
# 11. To turn ON the backlight:
#lcd.backlight_on()
# 12. To print a single character:
#lcd.putchar('x')
# 13. To print a custom character:
#happy_face = bytearray([0x00, 0x0A, 0x00, 0x04, 0x00, 0x11, 0x0E, 0x00])
#lcd.custom_char(0, happy_face)
#lcd.putchar(chr(0))

Test Result

The first line of the LCD1602 shows hello and the second line shows keyestudio.

Project 8.2 Dangerous Gas Alarm

Description

When a gas sensor detects a high concentration of dangerous gas, the buzzer will sound an alarm and the display will show dangerous.

Component Knowledge

MQ2 Smoke Sensor:

It is a gas leak monitoring device for homes and factories, which is suitable for liquefied gas, benzene, alkyl, alcohol, hydrogen as well as smoke detection. Our sensor leads to digital pin D and analog output pin A, which is connected to D as a digital sensor in this project .

Control Pin

Gas Sensor	23
\

Test Code

from time import sleep_ms, ticks_ms
from machine import SoftI2C, Pin
from i2c_lcd import I2cLcd

DEFAULT_I2C_ADDR = 0x27

scl_pin = Pin(22, Pin.OUT, pull=Pin.PULL_UP)  # GPIO22 with internal pull-up enabled
sda_pin = Pin(21, Pin.OUT, pull=Pin.PULL_UP)  # GPIO21 with internal pull-up enabled

i2c = SoftI2C(scl=Pin(22), sda=Pin(21), freq=100000)
lcd = I2cLcd(i2c, DEFAULT_I2C_ADDR, 2, 16)

from machine import Pin
import time
gas = Pin(23, Pin.IN, Pin.PULL_UP)

while True:
    gasVal = gas.value()  # Reads the value of button 1
    print("gas =",gasVal)  #Print it out in the shell
    lcd.move_to(1, 1)
    lcd.putstr('val: {}'.format(gasVal))
    if(gasVal == 1):
        #lcd.clear()
        lcd.move_to(1, 0)
        lcd.putstr('Safety       ')
    else:
        lcd.move_to(1, 0)
        lcd.putstr('dangerous')
    time.sleep(0.1) #delay 0.1s

Test Result

The screen displays “safety” in normal state. However, when the gas sensor detects some dangerous gases, such as carbon monoxide, at a certain concentration, the buzzer will sound an alarm and the screen displays “dangerous”.