60 lines
1.6 KiB
Python
60 lines
1.6 KiB
Python
# SPDX-FileCopyrightText: 2021 Scott Shawcroft, written for Adafruit Industries
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#
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# SPDX-License-Identifier: MIT
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import time
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import board
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import microcontroller
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import rp2pio
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import adafruit_pioasm
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# NeoPixels are 800khz bit streams. We are choosing zeros as <312ns hi, 936 lo>
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# and ones as <700 ns hi, 556 ns lo>.
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# The first two instructions always run while only one of the two final
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# instructions run per bit. We start with the low period because it can be
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# longer while waiting for more data.
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program = """
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.program ws2812
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.side_set 1
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.wrap_target
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bitloop:
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out x 1 side 0 [6]; Drive low. Side-set still takes place before instruction stalls.
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jmp !x do_zero side 1 [3]; Branch on the bit we shifted out previous delay. Drive high.
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do_one:
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jmp bitloop side 1 [4]; Continue driving high, for a one (long pulse)
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do_zero:
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nop side 0 [4]; Or drive low, for a zero (short pulse)
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.wrap
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"""
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assembled = adafruit_pioasm.assemble(program)
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# If the board has a designated neopixel, then use it. Otherwise use
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# GPIO16 as an arbitrary choice.
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if hasattr(board, "NEOPIXEL"):
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NEOPIXEL = board.NEOPIXEL
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else:
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NEOPIXEL = microcontroller.pin.GPIO16
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sm = rp2pio.StateMachine(
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assembled,
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frequency=12_800_000, # to get appropriate sub-bit times in PIO program
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first_sideset_pin=NEOPIXEL,
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auto_pull=True,
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out_shift_right=False,
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pull_threshold=8,
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)
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print("real frequency", sm.frequency)
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for i in range(30):
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sm.write(b"\x0a\x00\x00")
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time.sleep(0.1)
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sm.write(b"\x00\x0a\x00")
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time.sleep(0.1)
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sm.write(b"\x00\x00\x0a")
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time.sleep(0.1)
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print("writes done")
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time.sleep(2)
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