HackSpace_-_April_2020

FORGE

1. Ground


2. Power


3. Contrast


4. Register Select


5. Read/Write


6. Enable


7. Data 0


8. Data 1


9. Data 2


10. Data 3


11. Data 4


12. Data 5


13. Data 6


14. Data 7


15. Backlight positive


16. Backlight negative

You don’t need all of these pins. Power and ground
obviously need to be connected to power and ground.
Contrast takes a voltage, and the easiest way to create
an adjustable voltage (and therefore giving you a way
of controlling the contrast on the screen) is to create a
voltage divider with a potentiometer. Connect the pin
on one side of the potentiometer to power, the other
side to ground, and the middle one to the contrast
pin. This way, you can vary the look of the display by
twiddling the knob.
Read/write should be connected to ground. You’ll
need six pins on your microcontroller that take register
select, enable, and Data 4–7. Any digital pins should
do. We used an Adafruit Grand Central and pins 21,
19, 17, 16, 15, 14 respectively, but change these out
as you need.
The backlight should also be connected to power.
You might need a resistor to protect this – take a look
at your device’s data sheet or, if you’re not sure, use a
220 ohm resistor just to be safe.

SHOW US THE CODE

We’ll start by looking at how to control this display

with CircuitPython (we’ll take a look at Arduino next).

The following code sets up the LCD and displays the

classic first text, ‘Hello world’.

import board

import digitalio

import adafruit_character_lcd.character_lcd as

characterlcd

import time

lcd_rs = digitalio.DigitalInOut(board.D21)

lcd_en = digitalio.DigitalInOut(board.D19)

lcd_d7 = digitalio.DigitalInOut(board.D14)

lcd_d6 = digitalio.DigitalInOut(board.D15)

lcd_d5 = digitalio.DigitalInOut(board.D16)

lcd_d4 = digitalio.DigitalInOut(board.D17)

lcd_columns = 16

lcd_rows = 2

lcd = characterlcd.Character_LCD_Mono(lcd_rs, lcd_

en, lcd_d4, lcd_d5, lcd_d6, lcd_d7, lcd_columns,

lcd_rows)

lcd.message = “Hello\nworld”

while True:

pass

As you can see, there’s not a huge amount we need

to get everything working. We just need to create

Character_LCD_Mono object using the connections

we’ve used. Once we’ve got this, we can set the

message property to the message we want to display.

As you can see, the message contains the \n newline

character, which makes our test display on two lines.

Using it like this, we can easily send whatever text

we want to the little screen, and it will be displayed for

all the world to see. However, we don’t need to stop

here. There are even more features we can explore to

make our display a little more interesting.

Above

CircuitPython is now

running on over 100

different boards

Below

Adding output to your

Arduino projects has

never been easier