CircuitPython GC9A01 demos

Demos showing how to use CircuitPython displayio driver for GC9A01-based round LCDs. This driver is available in the CircuitPython Community Bundle, or you can install it by hand by copying the gc9a01.py file to your CIRCUITPY/lib directory, or use circup install gc9a01.

Usage

import board
import displayio
import gc9a01
# Raspberry Pi Pico pinout, one possibility, at "southwest" of board
tft_clk = board.GP10 # must be a SPI CLK
tft_mosi= board.GP11 # must be a SPI TX
tft_rst = board.GP12
tft_dc  = board.GP13
tft_cs  = board.GP14
tft_bl  = board.GP15
spi = busio.SPI(clock=tft_clk, MOSI=tft_mosi)
display_bus = displayio.FourWire(spi, command=tft_dc, chip_select=tft_cs, reset=tft_rst)
display = gc9a01.GC9A01(display_bus, width=240, height=240, backlight_pin=tft_bl)

# ... normal circuitpython displayio stuff

Installation

Each of the .py files in "examples" is its own demo. Copy one of these to be your CIRCUITPY's "code.py", like:

cp gc9a01_hellocircles.py /Volumes/CIRCUITPY/code.py

You'll need to install various libraries. Most notably the gc9a01 library. You may also need the adafruit_display_text and adafruit_imageload, depending on the example. The easiest way to install these is from a terminal:

circup install gc9a01
circup install adafruit_display_text
circup install adafruit_imageload

Examples

Check out the 'examples' directory for complete examples:

• 'gc9a01_helloworld' -- shows one way of doing polar coordinates
• 'gc9a01_hellocircles' -- similar to above but with floating circles using vectorio
• 'gc9a01_picture_locket' -- display a series of pictures, makes a nice locket if used with a QT Py Haxpress
• 'gc9a01_gauge_knob' -- round dial gauge using gauge background & dial bitmaps, showing bitmaptools.rotozoom

The examples attempt to auto-detect the board you're using. The currently detected boards:

• QT Py M0 Haxpress
• QT Py RP2040
• Raspberry Pi Pico
• ItsyBitsy M4 Express

Wiring

Wiring is dependent on board you're hooking it up to. The "SCL" and "SDA" lines need to be hooked up to SPI pins "SCK" and "MOSI/TX". The gc9a01_helloworld.py has example wirings for three different boards. Here is an example for the Pico:

• VCC - Pico 3.3V(out)
• Gnd - Pico Ground
• SCL - Pico GP10 (SPI1 SCK)
• SDA - Pico GP11 (SPI1 TX)
• RES - Pico GP12
• DC - Pico GP13
• CS - Pico GP14
• BLK - Pico GP15 (can be omitted if you don't need backlight brightness control)

Here is an example for a QT Py Haxpress:

• VCC - QT Py 3.3V
• Gnd - QT Py Ground
• SCL - QT Py SCK
• SDA - QT Py MO
• RES - QT Py TX
• DC - QT Py A3
• CS - QT Py A2
• BLK - unconnected

Building your own dial gauges

There is a partial Python port of @bikerglen's gauge-generator in docs/gauge-generator. These scripts use the wonderful Wand Python wrapper for ImageMagick's C API.

Future Project Ideas:

• bargraph display using vectorio

Notes to self:

• This repo started out as a GC9A01 driver for CircuitPython, but @tylercrumpton beat me to the CircuitPython Community Bundle by a few days. Now it's a repo of demos