74 lines
3.3 KiB
Python
74 lines
3.3 KiB
Python
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import framebuf
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class fbuf(framebuf.FrameBuffer):
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filled=0
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clear=1
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def __init__(self, width, height):
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self.width=width
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self.height=height
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self.buffer=bytearray(width*height//8)
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super().__init__(self.buffer, width, height, framebuf.MONO_HLSB)
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self.fill(self.clear)
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class epaper:
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def __init__(self, width, height, refresh_delay=7800, pin_mosi=23, pin_miso=19, pin_sck=18, pin_cs=2, pin_dc=4, pin_rst=0, pin_busy=15, spi_device=2):
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self.width=width
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self.height=height
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self.refresh_delay=refresh_delay
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self.black=fbuf(width, height)
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self.red=fbuf(width, height)
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from epaper1in54b import EPD
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from machine import Pin, SPI
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self.mosi=Pin(pin_mosi)
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self.miso=Pin(pin_miso)
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self.sck=Pin(pin_sck)
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self.cs=Pin(pin_cs)
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self.dc=Pin(pin_dc)
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self.rst=Pin(pin_rst)
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self.busy=Pin(pin_rst)
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self.spi=SPI(spi_device,baudrate=200000,polarity=0,phase=0,mosi=self.mosi,miso=self.miso,sck=self.sck)
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self.epd=EPD(self.spi,cs=self.cs,dc=self.dc,rst=self.rst,busy=self.busy)
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#only needs to be run once upon startup, unless the display is placed into low-power mode
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#using epd.sleep(), then you need to run either epd.init() or epd.reset()
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self.epd.init()
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def show(self):
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#reset() appears not to put the display into a state where it will accept new input
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self.epd.init()
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self.epd.display_frame(self.black.buffer, self.red.buffer)
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#display_frame returns as soon as data is sent to the display and the refresh has been initiated
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#so if we immediately sleep(), the display is never refreshed
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#thus we wait 7 seconds (manufacturer specified redraw time)
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self.sleep_ms(self.refresh_delay)
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self.epd.sleep()
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def sleep_ms(self, time):
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from time import sleep_ms
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sleep_ms(time)
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#confusingly, a 1 (interpreted in the display as 0xff) is the "off", or "empty" state for the pixel
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#whereas a 0 is the "on", or "filled" state
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#set up framebuffers and backing buffers
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#because we have a display with three colours (red, white, black), this is presented logically
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#as two separate monochrome "frames" of equal size
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#so when rendering, the display_frame function will take as many frames as there are non-white colours
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#this could be used for easy inversion by just swapping the order of arguments to display_frame(buf,buf)
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#some documentation suggests that framebuffer should be initialised directly
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#using FrameBuffer(bytearray(size..))
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#however this causes problems when trying to use the fb as a buffer
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#because it is not "subscriptable"
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#thus the underlying buffer MUST be separated, as it cannot be directly read from inside the fb
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#set up SPI, then set up the ePaper display
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#i'm using a WaveShare ePaper SPI 1.54in. display model (B) with a third colour (red)
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#this example code will work identically for the model (C) with yellow as its third colour
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#but is easily adaptable for other waveshare displays
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#TODO make this configurable
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#SPI is one of the more poorly documented parts of the micropython esp32 port
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#i wish i could make this prettier
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#for power saving niceness, we reset before drawing, and sleep afterwards.
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#result of this is that the display may redden a bit but will draw less power
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#TODO figure out if there's a way to have the display only redraw the red or black, at present it redraws both
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