scorpio.py

# SPDX-FileCopyrightText: 2016 Damien P. George
# SPDX-FileCopyrightText: 2017 Scott Shawcroft for Adafruit Industries
# SPDX-FileCopyrightText: 2019 Carter Nelson
# SPDX-FileCopyrightText: 2019 Roy Hooper
# SPDX-FileCopyrightText: 2020 Jeff Epler
#
# SPDX-License-Identifier: MIT

"""
`scorpio` - Neopixel strip driver using RP2040's PIO
===================================================

* Author(s): Damien P. George, Scott Shawcroft, Carter Nelson, Roy Hooper, Jeff Epler
"""

import adafruit_pioasm
import bitops
import microcontroller
import _pixelbuf
import rp2pio

_program = """
.program piopixl8
.side_set 2
; NeoPixels are 800kHz bit streams.  Zeros are 1/3 duty cycle and ones are 2/3 duty cycle.
; 1 loop = 6 cycles, so the PIO peripheral needs to run at 1.2MHz.
; x must be pre-loaded with zero so we can set all-ones (with mov pins, !x)
; or all-zeros (with mov pins, x)
    pull ifempty ; don't start outputting HIGH unless data is available
    mov pins, ~ x [1]; always-high part
    out pins, 8 [1] ; variable part
    mov pins, x ; always-low part
"""

_assembled = adafruit_pioasm.assemble(_program)

# Pixel color order constants
RGB = "RGB"
"""Red Green Blue"""
GRB = "GRB"
"""Green Red Blue"""
RGBW = "RGBW"
"""Red Green Blue White"""
GRBW = "GRBW"
"""Green Red Blue White"""

_gpio_order = [getattr(microcontroller.pin, f"GPIO{i}", None) for i in range(32)]

def _pin_directly_follows(a, b):
    if a not in _gpio_order or b not in _gpio_order:
        return False
    return _gpio_order.index(a) + 1 == _gpio_order.index(b)

class Scorpio(_pixelbuf.PixelBuf):
    """
    A sequence of neopixels.

    :param ~microcontroller.Pin data0: The first of 8 data registers, in GPIO order
    :param int n: The total number of neopixels.  Must be a multiple of the number of strands.
    :param int num_strands: The number of neopixels in each strand.
    :param int bpp: Bytes per pixel. 3 for RGB and 4 for RGBW pixels.
    :param float brightness: Brightness of the pixels between 0.0 and 1.0 where 1.0 is full
      brightness
    :param bool auto_write: True if the neopixels should immediately change when set. If False,
      `show` must be called explicitly.
    :param str pixel_order: Set the pixel color channel order. GRBW is set by default.

    Example for Raspberry Pi Pico:

    .. code-block:: python

        pixels = scorpio.NeoPIO(board.GP0, board.GP1, board.GP2, 8*30, auto_write=False)
        pixels.fill(0xff0000)
        pixels.show()

    .. py:method:: NeoPIO.show()

        Shows the new colors on the pixels themselves if they haven't already
        been autowritten.

        The colors may or may not be showing after this function returns because
        it may be done asynchronously.

    .. py:method:: NeoPIO.fill(color)

        Colors all pixels the given ***color***.

    .. py:attribute:: brightness

        Overall brightness of the pixel (0 to 1.0)

    """

    def __init__(
        self, data0, n, *, num_strands=8, bpp=3, brightness=1.0,
        auto_write=True, pixel_order=None
    ):
        if n % num_strands:
            raise ValueError("Length must be a multiple of num_strands")
        if not pixel_order:
            pixel_order = GRB if bpp == 3 else GRBW
        else:
            if isinstance(pixel_order, tuple):
                order_list = [RGBW[order] for order in pixel_order]
                pixel_order = "".join(order_list)

        super().__init__(
            n, brightness=brightness, byteorder=pixel_order, auto_write=auto_write
        )

        self._transposed = bytearray(bpp*n*8//num_strands)
        self._num_strands = num_strands

        self._sm = rp2pio.StateMachine(
            _assembled,
            frequency=800_000 * 6,
            init=adafruit_pioasm.assemble("set pindirs 7\nset x 0"),
            first_out_pin=data0,
            out_pin_count=8,
            first_set_pin=data0,
            auto_pull=True,
            out_shift_right=False,
            pull_threshold=8,
        )


    def deinit(self):
        """Blank out the neopixels and release the state machine."""
        self.fill(0)
        self.show()
        self._sm.deinit()

    def __enter__(self):
        return self

    def __exit__(self, exception_type, exception_value, traceback):
        self.deinit()

    def __repr__(self):
        return "[" + ", ".join([str(x) for x in self]) + "]"

    @property
    def n(self):
        """
        The total number of neopixels in all strands (read-only)
        """
        return len(self)

    @property
    def num_strands(self):
        """
        The total number of neopixels in all strands (read-only)
        """
        return self._num_strands

    def _transmit(self, buffer):
        bitops.bit_transpose(buffer, self._transposed, self._num_strands)
        self._sm.write(self._transposed)