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Interfacing 16x2 LCD display with Raspberry Pi Pico & MicroPython

#raspberry pi pico #raspberry pi pico 2 #raspberry pi pico w #raspberry pi pico 2W #micro python #guide

16x2 lcd

Table of Contents

Abstract

In this article, a comprehensive step-by-step guide to interface 16x2 LCD display with Raspberry Pi Pico board using MicroPython. Raspberry Pi Pico has 4 different variants (Pico, Pico 2, Pico W, Pico 2W) supporting micro-python. This articles lays the foundation for more advanced embedded system and IoT projects.

🧭 Pre-Request

  • OS : Windows / Linux / Mac / Chrome
  • Thonny IDE.
  • MicroPython firmware in Raspberry Pi Pico / Pico 2 / Pico W / Pico 2W.

Hardware Required

  • Raspberry Pi Pico / Pico 2 / Pico W / Pico 2W.
  • 16x2 LCD.
  • Potentiometer (POT)
  • Resistor.
  • BreadBoard.
  • Micro USB Cable.
  • Connecting wires.
  • 5V DC power supply (Optional)
Components Purchase Link
Raspberry Pi Pico link
Raspberry Pi Pico 2 link
Raspberry Pi Pico W link
Raspberry Pi Pico 2W link
16x2 LCD link
Potentiometer (POT) link
BreadBoard large : small
Connecting Wires link
Micro USB Cable link
5V DC Adaptor link

Don't own a hardware 😢

No worries,

Still you can learn using simulation. check out simulation part 😃.

Connection Table

16x2 LCD can be connected in 4 wire and 8 wire mode. In this article 4 wire mode is demonstrated, as 8 wire mode is rarely used now a days.

Info

With I2C LCD interface, we can interface 16x2 LCD display in 2 wire mode. click here to know how to interface 16x2 LCD display in serial mode using 2 wire system.

16x2 LCD GPIO Remarks
VSS (1) GND Ground
VCC (2) +5 V +5V of Board or External 5V DC Supply
VEE (3) -- POT variable terminal as shown in circuit
RS (4) 15 Register Select Pin
RW (5) GND Read / Write Pin
E (6) 14 Enable Pin
D0 to D3 -- No connection (∵ 4 wire mode)
D4 (11) 13 Data line 4
D5 (12) 12 Data line 5
D6 (13) 11 Data line 6
D7 (14) 10 Data line 7
A (15) -- +5V of Board or External 5V DC Supply
K (16) -- Ground through Resistor

Note

  • To control the backlight led programmatically. LCD Pin A(15) can be connected to GPIO.
  • VCC (2) can be connected to external +5 V DC supply or to the VBUS pin number 40 of Raspberry Pi Pico Board.
  • While using External 5 V supply for 16x2 LCD, make sure ground pin of External Supply and Pico board is connected.

Circuit Diagram

fig-Connection Diagram

📂 Code

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import utime
from lcd_api import LCD_16x2_parallel


# LCD_16x2_parallel(rs, e, d4, d5, d6, d7)
lcd = LCD_16x2_parallel(15, 14, 13, 12, 11, 10)

# Set cursor to Row 1, Column 1
lcd.returnHome()
lcd.display("  Aavishkarah   ")
utime.sleep_ms(2000)

# Move to LCD (2, 0) position 
# Row 2 and Column 1 
lcd.setCursor(2,0)
lcd.display("---Simulation---" , 100)
utime.sleep_ms(2000)


# Clear the Screen
lcd.clearScreen()
lcd.display("Check Link for", 150)
lcd.setCursor(2,0)
lcd.display("more details" , 150)
utime.sleep_ms(2000)

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from machine import Pin
import utime

class LCD_16x2_parallel:

    def __init__(self, rs, e, d4, d5, d6, d7):
        self.rs = Pin(rs, Pin.OUT)
        self.e = Pin(e, Pin.OUT)
        self.d4 = Pin(d4, Pin.OUT)
        self.d5 = Pin(d5, Pin.OUT)
        self.d6 = Pin(d6, Pin.OUT)
        self.d7 = Pin(d7, Pin.OUT)
        self.setupLCD()

    def setupLCD(self):
        self.rs.value(0)
        self.send2LCD4(0b0011)
        self.send2LCD4(0b0011)
        self.send2LCD4(0b0011)
        self.send2LCD4(0b0010)
        self.send2LCD8(0b00101000)
        self.send2LCD8(0b00001100)#lcd on, blink off, cursor off.
        self.send2LCD8(0b00000110)#increment cursor, no display shift
        self.send2LCD8(0b00000001)#clear screen
        self.longDelay(2)#clear screen needs a long delay
        self.rs.value(1)

    def send2LCD4(self,BinNum):
        self.d4.value((BinNum & 0b00000001) >>0)
        self.d5.value((BinNum & 0b00000010) >>1)
        self.d6.value((BinNum & 0b00000100) >>2)
        self.d7.value((BinNum & 0b00001000) >>3)
        self.pulseE()

    def pulseE(self):
        self.e.value(1)
        utime.sleep_us(40)
        self.e.value(0)
        utime.sleep_us(40)

    def longDelay(self, t):
        utime.sleep_ms(t)

    def shortDelay(self,t):
        utime.sleep_us(t)

    def send2LCD4(self,BinNum):
        self.d4.value((BinNum & 0b00000001) >>0)
        self.d5.value((BinNum & 0b00000010) >>1)
        self.d6.value((BinNum & 0b00000100) >>2)
        self.d7.value((BinNum & 0b00001000) >>3)
        self.pulseE()

    def send2LCD8(self,BinNum):
        self.d5.value((BinNum & 0b00100000) >>5)
        self.d4.value((BinNum & 0b00010000) >>4)
        self.d6.value((BinNum & 0b01000000) >>6)
        self.d7.value((BinNum & 0b10000000) >>7)
        self.pulseE()
        self.d4.value((BinNum & 0b00000001) >> 0)
        self.d5.value((BinNum & 0b00000010) >> 1)
        self.d6.value((BinNum & 0b00000100) >> 2)
        self.d7.value((BinNum & 0b00001000) >> 3)
        self.pulseE()

    def setCursor(self, line, pos):
        b = 0
        if line==1:
            b=0
        elif line==2:
            b=40
        self.returnHome()
        for i in range(0, b+pos):
            self.moveCursorRight()

    def returnHome(self):
        self.rs.value(0)
        self.send2LCD8(0b00000010)
        self.rs.value(1)
        self.longDelay(2)

    def moveCursorRight(self):
        self.rs.value(0)
        self.send2LCD8(0b00010100)
        self.rs.value(1)

    def display(self, data, ms=0):
        for x in str(data):
            self.send2LCD8(ord(x))
            utime.sleep_ms(ms)

    def clearScreen(self):
        self.returnHome()
        self.display(" "*16)
        self.setCursor(2,0)
        self.display(" "*16)
        self.returnHome()

Code Explanation

👉 Imports

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import utime
from lcd_api import LCD_16x2_parallel
  • time module for creating delay.
  • lcd_api module for interacting with 16x2 lcd display hardware.

👉 Instance of LCD display object.

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# LCD_16x2_parallel(rs, e, d4, d5, d6, d7)
lcd = LCD_16x2_parallel(15, 14, 13, 12, 11, 10)
  • Creating the instance of LCD_16x2_parallel object.
  • Depending upon your connection, change the GPIO pin numbers.
    • (rs, e, d4, d5, d6, d7)
    • As per the above connection table LCD_16x2_parallel(15, 14, 13, 12, 11, 10)

👉 Displaying the content

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# Set cursor to Row 1, Column 1
lcd.returnHome()
lcd.display("  Aavishkarah   ")
utime.sleep_ms(2000)
  • lcd.returnHome() method sets the display cursor to Row 1 and Column 1
  • The content to be displayed is passed to lcd.display() method.
    • âš  Make sure, the content is less than or equal to 16 Characters.
  • A delay of 2 seconds is given, so that the user can view the content before new content is displayed.

👉 Shifting the cursors and typewriting effect.

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# Move to LCD (2, 0) position 
# Row 2 and Column 1 
lcd.setCursor(2,0)
lcd.display("---Simulation---" , 100)
utime.sleep_ms(2000)


# Clear the Screen
lcd.clearScreen()
  • Each row can display 16 characters.
  • To continue the display content, we need to set the cursor to Row 2, Column 1
  • Setting of cursor to Row 2 and Column 1 is achieved by lcd.setCursor(2,0) method.
  • As discussed in the previous code section, display method takes the data to be displayed on the LCD screen.
  • To have a Typewriting effect, 2nd argument of delay in milli seconds can be passed.
    • In line 16, a delay of 100 ms is passed.
    • This adds a delay of 100 ms delay between the display of the letters.
  • Clearing1 the screen to display the new data is achieved by lcd.clearScreen() method.
    • Using clearScreen method also brings the cursor to the starting position (Row 1 and Column 1)

Try It

  • Alter the output content on the display by passing your data argument to the display method.
  • Observe the typing effect in the content display by altering the delay value of display(<data>, <delay>) method.

Simulation

Not able to view the simulation

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Extras

Components details

Modules / Libraries Used

  • time
    • time module provides functions related to date & time, measuring time intervals and generating delays.
    • More Details
  • lcd_api
    • To interact with 16x2 LCD display.
    • It is a third part library or user defined library.