ST7789 Driver for MicroPython

This driver is based on devbis' st7789_mpy driver. I modified the original driver for one of my projects to add:

• Display Rotation.
• Scrolling
• Writing text using bitmaps converted from True Type fonts
• Drawing text using 8 and 16 bit wide bitmap fonts
• Drawing text using Hershey vector fonts
• Drawing JPG's, including a SLOW mode to draw jpg's larger than available ram using the TJpgDec - Tiny JPEG Decompressor R0.01d. from http://elm-chan.org/fsw/tjpgd/00index.html
• Drawing and rotating Polygons and filled Polygons.
• Tracking bounds
• Support for st7735 displays

Included are 12 bitmap fonts derived from classic pc text mode fonts, 26 Hershey vector fonts and several example programs for different devices.

Display Configuration

Some displays may use a BGR color order or iverted colors. The cfg_helper.py program can use used to determine the color order, inversion_mode, colstart, and rowstart values needed for a display.

Color Modes

You can test the color order needed by a display by filling the display with the st7789.RED color and observing the color displayed.

• If the display is RED, the settings are correct.
• If the display is BLUE, color_order should be st7789.BGR.
• If the display is YELLOW, inversion_mode should be True.
• If the display is CYAN, color_order should be st7789.BGR and inversion_mode should be True.

colstart and rowstart

Some displays have a frame buffer memory larger than the physical LCD or LED matrix. In these cases the driver must be configured with the position of the first physcial column and row pixels relative to the frame buffer. Each rotation setting of the display may require different colstart and rowstart values.

The driver automatically adjusts the colstart and rowstarts values for common 135x240, 240x240 and 240x320 displays. These values can be overridden using the offsets method if the default values do not work for your display. The offsets method should be called after any calls of the rotation method.

128x128 st7735 cfg_helper.py example

inversion_mode(False)
color_order = st7789.BGR
for rotation 0 use offset(2, 1)
for rotation 1 use offset(1, 2)
for rotation 2 use offset(2, 3)
for rotation 3 use offset(3, 2)

128x160 st7735 cfg_helper.py example

inversion_mode(False)
color_order = st7789.RGB
for rotation 0 use offset(0, 0)
for rotation 1 use offset(0, 0)
for rotation 2 use offset(0, 0)
for rotation 3 use offset(0, 0)

Pre-compiled firmware files

The firmware directory contains pre-compiled firmware for various devices with the st7789 C driver and frozen python font files. See the README.md file in the fonts folder for more information on the font files.

MicroPython v1.17-20-g0a5107372 compiled with ESP IDF v4.2 using CMake

Directory	File	Device
GENERIC-7789	firmware.bin	Generic ESP32 devices
GENERIC_SPIRAM-7789	firmware.bin	Generic ESP32 devices with SPI Ram
PYBV11	firmware.dfu	Pyboard v1.1
RP2	firmware.uf2	Raspberry Pi Pico RP2040
T-DISPLAY	firmware.bin	LILYGO® TTGO T-Display
T-Watch-2020	firmware.bin	LILYGO® T-Watch 2020

Additional Modules

Module	Source
axp202c	https://github.com/lewisxhe/AXP202X_Libraries
focaltouch	https://gitlab.com/mooond/t-watch2020-esp32-with-micropython

Video Examples

Example	Video
PYBV11 hello.py	https://youtu.be/OtcERmad5ps
PYBV11 scroll.py	https://youtu.be/ro13rvaLKAc
T-DISPLAY fonts.py	https://youtu.be/2cnAhEucPD4
T-DISPLAY hello.py	https://youtu.be/z41Du4GDMSY
T-DISPLAY scroll.py	https://youtu.be/GQa-RzHLBak
T-DISPLAY roids.py	https://youtu.be/JV5fPactSPU
TWATCH-2020 draw.py	https://youtu.be/O_lDBnvH1Sw
TWATCH-2020 hello.py	https://youtu.be/Bwq39tuMoY4
TWATCH-2020 bitmap.py	https://youtu.be/DgYzgnAW2d8
TWATCH-2020 watch.py	https://youtu.be/NItKb6umMc4

This is a work in progress.

Thanks go out to:

• https://github.com/devbis for the original driver this is based on.
• https://github.com/hklang10 for letting me know of the new mp_raise_ValueError().
• https://github.com/aleggon for finding the correct offsets for a 240x240 display and discovering issues compiling for STM32 based boards.

-- Russ

Overview

This is a driver for MicroPython to handle cheap displays based on the ST7789 chip.

The driver is written in C. Firmware is provided for ESP32, ESP32 with SPIRAM, pyboard1.1, and Raspberry Pi Pico devices.

Setup MicroPython Build Environment in Ubuntu 20.04.2

Update and upgrade Ubuntu using apt-get if you are using a new install of Ubuntu or the Windows Subsystem for Linux.

sudo apt-get -y update
sudo apt-get -y upgrade

Use apt-get to install the required build tools.

sudo apt-get -y install build-essential libffi-dev git pkg-config cmake virtualenv python3-pip python3-virtualenv

Clone the esp-idf SDK repo & install -- this usually takes several minutes

git clone --recursive https://github.com/espressif/esp-idf.git
cd esp-idf/
./install.sh

Source the esp-idf export.sh script to set the required environment variables. It's important that you source the file and not run it using ./export.sh. You will need to source this file before compiling MicroPython.

source export.sh
cd ..

Clone the MicroPython repo.

git clone https://github.com/micropython/micropython.git

Clone the st7789 driver repo.

git clone https://github.com/russhughes/st7789_mpy.git

Update the git submodules and compile the micropython cross-compiler

cd micropython/
git submodule update --init
cd mpy-cross/
make
cd ..
cd ports/esp32

Copy any .py files you want to include in the firmware as frozen python modules to the modules subdirectory in ports/esp32. Be aware there is a limit to the flash space available. You will know you have exceeded this limit if you receive an error message saying the code won't fit in the partition or if your firmware continuously reboots with an error.

For example:

cp ../../../st7789_mpy/fonts/bitmap/vga1_16x16.py modules
cp ../../../st7789_mpy/fonts/truetype/NotoSans_32.py modules
cp ../../../st7789_mpy/fonts/vector/scripts.py modules

Build the MicroPython firmware with the driver and frozen .py files in the modules directory. If you did not add any .py files to the modules directory you can leave out the FROZEN_MANIFEST and FROZEN_MPY_DIR settings.

make USER_C_MODULES=../../../../st7789_mpy/st7789/micropython.cmake FROZEN_MANIFEST="" FROZEN_MPY_DIR=$UPYDIR/modules

Erase and flash the firmware to your device. Set PORT= to the ESP32's usb serial port. I could not get the usb serial port to work under the Windows Subsystem (WSL2) for Linux. If you have the same issue you can copy the firmware.bin file and use the Windows esptool.py to flash your device.

make USER_C_MODULES=../../../../st7789_mpy/st7789/micropython.cmake PORT=/dev/ttyUSB0 erase
make USER_C_MODULES=../../../../st7789_mpy/st7789/micropython.cmake PORT=/dev/ttyUSB0 deploy

The firmware.bin file will be in the build-GENERIC directory. To flash using the python esptool.py utility. Use pip3 to install the esptool if it's not already installed.

pip3 install esptool

Set PORT= to the ESP32's usb serial port

esptool.py --port COM3 erase_flash
esptool.py --chip esp32 --port COM3 write_flash -z 0x1000 firmware.bin

CMake building instructions for MicroPython 1.14 and later

for ESP32:

$ cd micropython/ports/esp32

And then compile the module with specified USER_C_MODULES dir

$ make USER_C_MODULES=../../../../st7789_mpy/st7789/micropython.cmake

for Raspberry Pi PICO:

$ cd micropython/ports/rp2

And then compile the module with specified USER_C_MODULES dir

$ make USER_C_MODULES=../../../st7789_mpy/st7789/micropython.cmake

Working examples

This module was tested on ESP32, STM32 based pyboard v1.1 and the Raspberry Pi Pico. You have to provide a SPI object and the pin to use for the `dc' input of the screen.

# ESP32

import machine
import st7789
spi = machine.SPI(2, baudrate=40000000, polarity=1, sck=machine.Pin(18), mosi=machine.Pin(23))
display = st7789.ST7789(spi, 240, 240, reset=machine.Pin(4, machine.Pin.OUT), dc=machine.Pin(2, machine.Pin.OUT))
display.init()

I was not able to run the display with a baud rate over 40MHZ.

Methods

• st7789.ST7789(spi, width, height, dc, reset, cs, backlight, rotation, color_order, buffer_size)

  Required positional arguments:

  • spi spi device
  • width display width
  • height display height

  Required keyword arguments:

  • dc sets the pin connected to the display data/command selection input. This parameter is always required.

  Optional keyword arguments:

  • reset sets the pin connected to the displays hardware reset input. If the displays reset pin is tied high the reset parameter is not required.

  • cs sets the pin connected to the displays chip select input. If the displays CS pin is tied low, the display must be the only device connected to the SPI port. The display will always be the selected device and the cs parameter is not required.

  • backlight sets the pin connected to the displays backlight enable input. The displays backlight input can often be left floating or disconnected as the backlight on some displays are always powered on and cannot be turned off.

  • rotation 0-0 degrees, 1-90 degrees, 2-180 degrees, 3-270 degrees

  • color_order set the color order used by the driver st7789.RGB and st7789.BGR are supported.

  • buffer_size If a buffer_size is not specified a dynamically allocated buffer is created and freed as needed. If a buffer_size is specified it must be large enough to contain the largest bitmap, font character and/or decoded JPG image used (Rows * Columns * 2 bytes, 16bit colors in RGB565 notation). Dynamic allocation is slower and can cause heap fragmentation so garbage collection (GC) should be enabled.

• on()

  Turn on the backlight pin if one was defined during init.

• off()

  Turn off the backlight pin if one was defined during init.

• pixel(x, y, color)

  Set the specified pixel to the given color.

• line(x0, y0, x1, y1, color)

  Draws a single line with the provided color from (x0, y0) to (x1, y1).

• hline(x, y, length, color)

  Draws a single horizontal line with the provided color and length in pixels. Along with vline, this is a fast version with reduced number of SPI calls.

• vline(x, y, length, color)

  Draws a single horizontal line with the provided color and length in pixels.

• rect(x, y, width, height, color)

  Draws a rectangle from (x, y) with corresponding dimensions

• fill_rect(x, y, width, height, color)

  Fill a rectangle starting from (x, y) coordinates

• blit_buffer(buffer, x, y, width, height)

  Copy bytes() or bytearray() content to the screen internal memory. Note: every color requires 2 bytes in the array

• text(font, s, x, y[, fg, bg])

  Write text to the display using the specified bitmap font with the coordinates as the upper-left corner of the text. The foreground and background colors of the text can be set by the optional arguments fg and bg, otherwise the foreground color defaults to WHITE and the background color defaults to BLACK. See the README.md in the fonts/bitmap directory for example fonts.

• write(bitap_font, s, x, y[, fg, bg])

  Write text to the display using the specified proportional or Monospace bitmap font module with the coordinates as the upper-left corner of the text. The foreground and background colors of the text can be set by the optional arguments fg and bg, otherwise the foreground color defaults to WHITE and the background color defaults to BLACK. See the README.md in the truetype/fonts directory for example fonts. Returns the width of the string as printed in pixels.

  The font2bitmap utility creates compatible 1 bit per pixel bitmap modules from Proportional or Monospaced True Type fonts. The character size, foreground, background colors and the characters to include in the bitmap module may be specified as parameters. Use the -h option for details. If you specify a buffer_size during the display initialization it must be large enough to hold the widest character (HEIGHT * MAX_WIDTH * 2).

• write_len(bitap_font, s)

  Returns the width of the string in pixels if printed in the specified font.

• draw(vector_font, s, x, y[, fg, scale])

  Draw text to the display using the specified hershey vector font with the coordinates as the lower-left corner of the text. The foreground color of the text can be set by the optional argument fg, otherwise the foreground color defaults to WHITE. The size of the text can be scaled by specifying a scale value. The scale value must be larger then 0 and can be a floating point or an integer value. The scale value defaults to 1.0. See the README.md in the vector/fonts directory for example fonts and the utils directory for a font conversion program.

• jpg(jpg_filename, x, y [, method])

  Draw JPG file on the display at the given x and y coordinates as the upper left corner of the image. There memory required to decode and display a JPG can be considerable as a full screen 320x240 JPG would require at least 3100 bytes for the working area + 320x240x2 bytes of ram to buffer the image. Jpg images that would require a buffer larger than available memory can be drawn by passing SLOW for method. The SLOW method will draw the image a piece at a time using the Minimum Coded Unit (MCU, typically 8x8) of the image.

• polygon_center(polygon)

  Return the center of the polygon as an (x, y) tuple. The polygon should consist of a list of (x, y) tuples forming a closed convex polygon.

• fill_polygon(polygon, x, y, color[, angle, center_x, center_y])

  Draw a filled polygon at the x, y coordinates in the color given. The polygon may be rotated angle radians about the center_x and center_y point. The polygon should consist of a list of (x, y) tuples forming a closed convex polygon.

  See the TWATCH-2020 watch.py demo for an example.

• polygon(polygon, x, y, color, angle, center_x, center_y)

  Draw a polygon at the x, y coordinates in the color given. The polygon may be rotated angle radians a bout the center_x and center_y point. The polygon should consist of a list of (x, y) tuples forming a closed convex polygon.

  See the T-Display roids.py for an example.

• bounding([status])

  Bounding turns on and off tracking the area of the display that has been written to. Initially tracking is disabled, pass a True value to enable tracking and False to disable. Passing a True or False parameter will reset the current bounding rectangle to (display_width, display_height, 0, 0).

  Returns a four integer tuple containing (min_x, min_y, max_x, max_y) indicating the area of the display that has been written to since the last clearing.

  See the TWATCH-2020 watch.py demo for an example.

• bitmap(bitmap, x , y [, index])

  Draw bitmap using the specified x, y coordinates as the upper-left corner of the of the bitmap. The optional index parameter provides a method to select from multiple bitmaps contained a bitmap module. The index is used to calculate the offset to the beginning of the desired bitmap using the modules HEIGHT, WIDTH and BPP values.

  The imgtobitmap.py utility creates compatible 1 to 8 bit per pixel bitmap modules from image files using the Pillow Python Imaging Library.

  The monofont2bitmap.py utility creates compatible 1 to 8 bit per pixel bitmap modules from Monospaced True Type fonts. See the inconsolata_16.py, inconsolata_32.py and inconsolata_64.py files in the examples/lib folder for sample modules and the mono_font.py program for an example using the generated modules.

  The character sizes, bit per pixel, foreground, background colors and the characters to include in the bitmap module may be specified as parameters. Use the -h option for details. Bits per pixel settings larger than one may be used to create antialiased characters at the expense of memory use. If you specify a buffer_size during the display initialization it must be large enough to hold the one character (HEIGHT * WIDTH * 2).

• width()

  Returns the current logical width of the display. (ie a 135x240 display rotated 90 degrees is 240 pixels wide)

• height()

  Returns the current logical height of the display. (ie a 135x240 display rotated 90 degrees is 135 pixels high)

• rotation(r)

  Set the rotates the logical display in a clockwise direction. 0-Portrait (0 degrees), 1-Landscape (90 degrees), 2-Inverse Portrait (180 degrees), 3-Inverse Landscape (270 degrees)

• offset(x_start, y_start) The memory in the ST7789 controller is configured for a 240x320 display. When using a smaller display like a 240x240 or 135x240 an offset needs to added to the x and y parameters so that the pixels are written to the memory area that corresponds to the visible display. The offsets may need to be adjusted when rotating the display.

  For example the TTGO-TDisplay is 135x240 and uses the following offsets.

  Rotation	x_start	y_start
  0	52	40
  1	40	53
  2	53	40
  3	40	52

  When the rotation method is called the driver will adjust the offsets for a 135x240 or 240x240 display. Your display may require using different offset values, if so, use the offset method after rotation to set the offset values.

  The values needed for particular display may not be documented and may require some experimentation to determine the correct values. One technique is to draw a box the same size as the display and then make small changes to the offsets until the display looks correct. See the cfg_helper.py program in the examples folder for more information.

The module exposes predefined colors: BLACK, BLUE, RED, GREEN, CYAN, MAGENTA, YELLOW, and WHITE

Helper functions

• color565(r, g, b)

  Pack a color into 2-bytes rgb565 format

• map_bitarray_to_rgb565(bitarray, buffer, width, color=WHITE, bg_color=BLACK)

  Convert a bitarray to the rgb565 color buffer that is suitable for blitting. Bit 1 in bitarray is a pixel with color and 0 - with bg_color.

  This is a helper with a good performance to print text with a high resolution font. You can use an awesome tool https://github.com/peterhinch/micropython-font-to-py to generate a bitmap fonts from .ttf and use them as a frozen bytecode from the ROM memory.