GC9A01 Display 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

Included are 12 bitmap fonts derived from classic pc text mode fonts, 26 Hershey vector fonts and several example programs for different devices. The driver supports 240x240 displays.

Pre-compiled firmware files

The firmware directory contains pre-compiled firmware for various devices with the gc9a01 C driver and frozen python font files. See the README.md file in the fonts folder for more information on the font files.

MicroPython v1.15 compiled with ESP IDF v4.2 using CMake

Directory	File	Device
ESP32-GENERIC-GC9A01-4M	firmware.bin	Generic ESP32 devices
ESP32-GENERIC-GC9A01-16M	firmware.bin	Generic ESP32 devices
ESP32-GENERIC-SPIRAM-GC9A01-4M	firmware.bin	Generic ESP32 devices with SPI Ram
ESP32-GENERIC-SPIRAM-GC9A01-16M	firmware.bin	Generic ESP32 devices with SPI Ram
RP2	firmware.uf2	Raspberry Pi Pico RP2040

Additional Modules

Module	Source

This is a work in progress.

-- Russ

Overview

This is a driver for MicroPython to handle cheap displays based on the GC9A01 chip.

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

CMake building instructions for MicroPython 1.14 and later

Prepare build tools as described in the manual. You should follow the instruction for building MicroPython and ensure that you can build the firmware without this display module.

Clone this module alongside the MPY sources:

$ git clone https://github.com/russhughes/gc9a01_mpy.git

ESP32 Build Example:

$ cd micropython/ports/esp32

And then compile the module with specified USER_C_MODULES dir

$ make USER_C_MODULES=../../../../gc9a01_mpy/src/micropython.cmake all

Erase the target device if this is the first time uploading this firmware

$ make USER_C_MODULES=../../../../gc9a01_mpy/src/micropython.cmake erase

Upload the new firmware

$ make USER_C_MODULES=../../../../gc9a01_mpy/src/micropython.cmake deploy

Additional build parameters

Additional build parameters may be specified during the build, erase and upload operations by including them after the make command. For example you can specify the DEBUG flag, Upload BAUD rate, alternate partition.csv file for different flash sizes and the USB serial port.

  make -j 4 \
    DEBUG=1 \
    BOARD=GENERIC \
    BAUD=3000000 \
    PART_SRC=partitions-16MiB.csv \
    PORT=/dev/tty.SLAB_USBtoUART \
    USER_C_MODULES=../../../../gc9a01_mpy/src/micropython.cmake all

Working examples

This module was tested on ESP32 and the Raspberry Pi Pico. You need to provide a SPI object and the pin to use for the DC pin of the screen.

# ESP32

import machine
import gc9a01
spi = machine.SPI(2, baudrate=40000000, polarity=1, sck=machine.Pin(18), mosi=machine.Pin(23))
display = gc9a01.GC9A01(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 baudrate higher than 40MHZ.

Methods

gc9a01.GC9A01(spi, width, height, reset, dc, cs, backlight, rotation, buffer_size)

required args:

  `spi` spi device
  `width` display width
  `height` display height

optional args:

  `reset` reset pin
  `dc` dc pin
  `cs` cs pin
  `backlight` backlight pin
  `rotation` Orientation of display.
  `buffer_size` 0= buffer dynamically allocated and freed as needed.

  Rotation | Orientation
  -------- | --------------------
     0     | 0 degrees
     1     | 90 degrees
     2     | 180 degrees
     3     | 270 degrees
     4     | 0 degrees mirrored
     5     | 90 degrees mirrored
     6     | 180 degrees mirrored
     7     | 270 degrees mirrored

If buffer_size is specified it must be large enough to contain the largest bitmap, font character and/or JPG used (Rows * Columns *2 bytes). Specifying a buffer_size reserves memory for use by the driver otherwise memory required is allocated and free dynamicly as it is needed. Dynamic allocation can cause heap fragmentation so garbage collection (GC) should be enabled.

This driver supports only 16bit colors in RGB565 notation.

GC9A01.on()

Turn on the backlight pin if one was defined during init.
GC9A01.off()

Turn off the backlight pin if one was defined during init.
GC9A01.pixel(x, y, color)

Set the specified pixel to the given color.
GC9A01.line(x0, y0, x1, y1, color)

Draws a single line with the provided color from (x0, y0) to (x1, y1).
GC9A01.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.
GC9A01.vline(x, y, length, color)

Draws a single horizontal line with the provided color and length in pixels.
GC9A01.rect(x, y, width, height, color)

Draws a rectangle from (x, y) with corresponding dimensions
GC9A01.fill_rect(x, y, width, height, color)

Fill a rectangle starting from (x, y) coordinates
GC9A01.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
GC9A01.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.
GC9A01.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).
GC9A01.write_len(bitap_font, s)

Returns the width of the string in pixels if printed in the specified font.
GC9A01.draw(vector_font, s, x, y[, fg, bg])

Draw text to the display using the specified hershey vector font with the coordinates as the lower-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 vector/fonts directory for example fonts and the utils directory for a font conversion program.
GC9A01.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.
GC9A01.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).
GC9A01.width()

Returns the current logical width of the display. (ie a 135x240 display rotated 90 degrees is 240 pixels wide)
GC9A01.height()

Returns the current logical height of the display. (ie a 135x240 display rotated 90 degrees is 135 pixels high)
GC9A01.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)

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 which 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.

mcu786 / gc9a01_mpy