MicroPython - Sharp Memory Display driver

MicroPython driver for Sharp Memory Displays.

This driver was derived from the Adafruit CircuitPython version - Adafruit_CircuitPython_SharpMemoryDisplay - made by @ladyada and others. It has been enhanced as follows:

• the speed of display updates has been significantly improved and memory use reduced
• a clear() method has been added to trigger the built-in hardware screen clear

Features and performance

For the Adafruit 400x240 display using a SPI connection at 2 MHz from a Raspberry Pi Pico 2, full screen updates are possible in around 65 ms.

The driver builds in the facility to use the extended framebuffer methods large_text(), triangle() and circle() methods in the MicroPython FrameBuffer extension framebuf2.

Important

To prevent potential permanent burn-in on the display the polarity must be reversed at least every 2 hours. This can be achieved by refreshing the display with the show() method. See display datasheet and application note for further information.

Display connection

The display has an SPI interface, connections for SCLK, MOSI, CS are required.

Usage

The module code should be uploaded to the Raspberry Pico Pi (or other Microcontroller running MicroPython). The large font, triangle and circles extension is added by additionally uploading the framebuf2.py module code. (See framebuf2.)

Classes

The module includes the class SharpMemoryDisplay.

syntax:

display = sharp.SharpMemoryDisplay(
    width, 
    height, 
    spi,
    cs
)

• width (default 400) and height (default 240) define the size of the display
• spi is an SPI object. The SCL (clock) and MOSI (data) pins must be defined. MISO is not used.
• cs is a GPIO Pin object for Chip Select

Methods and Properties

In addition to all MicroPython's framebuffer drawing methods, the following methods and properties are available for controlling the display:

show(startline, endline) - this method updates the display from the framebuffer. Partial updates for rows between a startline and an endline are possible and are faster than a full screen update. Omit both these parameters to update the whole display.

clear() - this method clears the display (to colour 1). It does not change the contents of the framebuffer. To clear the framebuffer to white as well, call the framebuffer method fill(1).

Example usage

    from machine import Pin, SPI
    import sharp

    spi0 = SPI(0, baudrate=2_000_000, sck=Pin(18), mosi=Pin(19), miso=Pin(16))
    display = sharp_mlcd.SharpMemoryDisplay(400, 240, spi0, cs=Pin(15, Pin.OUT))

    display.fill(0)
    display.text('SHARP MEMORY DISPLAY', 0, 0, 1)
    display.text('driver', 0, 8, 1)
    display.show()

See [demo example](/sharp_mlcd demo.py) for more details. (The example code was written for 400x240 displays.)

Tested displays

This driver has been tested with a Raspberry Pi Pico 2 W running MicroPython 1.28.0 and an Adafruit 400x240 display. It should work with other Adafruit Sharp Memory Display breakout boards.

Version notes

version 0.4.005

• initial commit
• improves speed and memory usage vs Adafruit driver by adding the display line numbers and trailing zero bytes to the framebuffer and then using a sub-framebuffer for the display content. Thus avoiding slow and memory-costly extensions to a bytearray used in the Adafruit driver for updating the display
• possibility for partial screen updates added
• hardware-based screen clear() method included

Collaboration

Suggestions for improvements and pull requests are welcome.

References

Adafruit SHARP memory display breakouts documentation (links to datasheets can be found here)

Application Note: Sharp Memory LCDs: Theory, Interfacing, and Programming