LILYGO T-Display RP2040

LILYGO makes low-cost and high-quality microcontroller development boards that include small displays. Although most of their boards run on C programs on ESP-32 processors, they do have one that runs MicroPython on an RP2040. This "kit" is really just that development board placed on a breadboard. The device has two buttons on it which can be used to adjust the time.

This is a color 1.14 inch LCD display PS with 240*135 resolution. It uses the ST7789V chip that has an extreamly high quality driver created by Russ Hughes that allows for flicker-free drawing.

I purchased mine on Ebay for $10.66 and three dollars for shipping.

Although the display is too small for most robotic applications where the robot is on the floor and we are standing, it is a good example of how we can get both clocks and watches to look great. My hope is that LILYGO comes out with a larger display in the future.

Lilygo also sells their own "wearable" watch kits] for $35 to $45. However, I have not purchased any of these that can be programmed with an RP2040 and MicroPython yet. Here is a GitHub Page for the T-Watch that implies it might be on the way. Note that using this requires extensive knowledge of the ESP32 development system.

Getting Started

To use the ST7789V driver we MUST use a custom image provide by Rull Hughes. This is because the driver is written in low-level C code and the python driver requires it to be combiled into the firmware image.

I downloaded the custom image here:

T-DISPLAY RP2040 Firmware

I then held the Boot button down while I powered up the device.

I soldered my own header pins on the LILYGO and placed it on a breadboard. Unfortunatly this makes it impossible to hold down the boot button with the device on the breadboard.

Pinouts

The pinouts are very different from the Raspberry Pi Pico.

Config File

This implementation puts the driver in a hidden C program, but it does have a configuration file that we must upload and place in the /lib directory.

Here is a Link to the File for the T-Display RP2040

"""TTGO T-Display RP2040 display"""

from machine import Pin, SPI
from time import sleep
import st7789

TFA = 40    # top free area when scrolling
BFA = 40    # bottom free area when scrolling

def config(rotation=0, buffer_size=0, options=0):

    Pin(22, Pin.OUT, value=1)

    spi = SPI(0,
        baudrate=62500000,
        polarity=1,
        phase=0,
        sck=Pin(2, Pin.OUT),
        mosi=Pin(3, Pin.OUT),
        miso=None)

    return st7789.ST7789(
        spi,
        135,
        240,
        cs=Pin(5, Pin.OUT),
        dc=Pin(1, Pin.OUT),
        backlight=Pin(4, Pin.OUT),
        rotation=rotation,
        options=options,
        buffer_size=buffer_size)

Blink The Onboard LED

This red LED is on the bottom of the board.

Blink Timer example:

from machine import Pin, Timer
led = Pin(25,Pin.OUT)
tim = Timer()
def tick(timer):
    global led
    led.toggle()
tim.init(freq=2.5, mode=Timer.PERIODIC, callback=tick)

Display Example

"""
display-test.py
Fills the screen with red, green and blue
"""

from utime import sleep
import st7789
import tft_config
tft = tft_config.config(1)
tft.init()

while True:
    tft.fill(st7789.RED)
    sleep(1)
    tft.fill(st7789.GREEN)
    sleep(1)
    tft.fill(st7789.BLUE)
    sleep(1)

Drawing Text

For this example to work, you will need to load a font library into the /lib directory.

import random
import utime
import st7789
import tft_config
import vga2_bold_16x32 as font

tft = tft_config.config(1)
tft.init()

# draw text using a 16X32 font using blue text on a white background
tft.text(
        font,
        'Hello World!',
        tft.width()//2-100, # x position to start writing
        tft.height()//2-50, # y position
        st7789.BLUE, # font in blue
        st7789.WHITE # background in white
)

Referneces

Item on Aliexpress Sample GitHub repo: https://github.com/Xinyuan-LilyGO/LILYGO-T-display-RP2040

ST7789V Submodule: Russ Hughes GitHub Repo

Config: Sample Config File