116 lines
3.5 KiB
Python
116 lines
3.5 KiB
Python
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from machine import Pin
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from micropython import const
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import framebuf
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_DIGIT_0 = const(0x1)
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_DECODE_MODE = const(0x9)
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_NO_DECODE = const(0x0)
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_INTENSITY = const(0xa)
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_INTENSITY_MIN = const(0x0)
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_SCAN_LIMIT = const(0xb)
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_DISPLAY_ALL_DIGITS = const(0x7)
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_SHUTDOWN = const(0xc)
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_SHUTDOWN_MODE = const(0x0)
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_NORMAL_OPERATION = const(0x1)
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_DISPLAY_TEST = const(0xf)
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_DISPLAY_TEST_NORMAL_OPERATION = const(0x0)
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_MATRIX_SIZE = const(8)
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class Max7219(framebuf.FrameBuffer):
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"""
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Driver for MAX7219 8x8 LED matrices
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Example for ESP8266 with 2x4 matrices (one on top, one on bottom),
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so we have a 32x16 display area:
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>>> from machine import Pin, SPI
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>>> from max7219 import Max7219
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>>> spi = SPI(1, baudrate=10000000)
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>>> screen = Max7219(32, 16, spi, Pin(15))
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>>> screen.rect(0, 0, 32, 16, 1) # Draws a frame
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>>> screen.text('Hi!', 4, 4, 1)
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>>> screen.show()
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On some matrices, the display is inverted (rotated 180°), in this case
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you can use `rotate_180=True` in the class constructor.
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"""
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def __init__(self, width, height, spi, cs, rotate_180=False):
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# Pins setup
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self.spi = spi
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self.cs = cs
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self.cs.init(Pin.OUT, True)
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# Dimensions
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self.width = width
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self.height = height
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# Guess matrices disposition
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self.cols = width // _MATRIX_SIZE
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self.rows = height // _MATRIX_SIZE
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self.nb_matrices = self.cols * self.rows
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self.rotate_180 = rotate_180
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# 1 bit per pixel (on / off) -> 8 bytes per matrix
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self.buffer = bytearray(width * height // 8)
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format = framebuf.MONO_HLSB if not self.rotate_180 else framebuf.MONO_HMSB
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super().__init__(self.buffer, width, height, format)
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# Init display
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self.init_display()
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def _write_command(self, command, data):
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"""Write command on SPI"""
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cmd = bytearray([command, data])
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self.cs(0)
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for matrix in range(self.nb_matrices):
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self.spi.write(cmd)
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self.cs(1)
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def init_display(self):
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"""Init hardware"""
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for command, data in (
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(_SHUTDOWN, _SHUTDOWN_MODE), # Prevent flash during init
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(_DECODE_MODE, _NO_DECODE),
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(_DISPLAY_TEST, _DISPLAY_TEST_NORMAL_OPERATION),
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(_INTENSITY, _INTENSITY_MIN),
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(_SCAN_LIMIT, _DISPLAY_ALL_DIGITS),
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(_SHUTDOWN, _NORMAL_OPERATION), # Let's go
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):
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self._write_command(command, data)
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self.fill(0)
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self.show()
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def brightness(self, value):
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"""Set display brightness (0 to 15)"""
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if not 0 <= value < 16:
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raise ValueError('Brightness must be between 0 and 15')
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self._write_command(_INTENSITY, value)
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def show(self):
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"""Update display"""
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# Write line per line on the matrices
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for line in range(8):
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self.cs(0)
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for matrix in range(self.nb_matrices):
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# Guess where the matrix is placed
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row, col = divmod(matrix, self.cols)
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# Compute where the data starts
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if not self.rotate_180:
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offset = row * 8 * self.cols
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index = col + line * self.cols + offset
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else:
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offset = 8 * self.cols - row * self.cols * 8 - 1
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index = self.cols * (8 - line) - col + offset
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self.spi.write(bytearray([_DIGIT_0 + line, self.buffer[index]]))
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self.cs(1)
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