44 lines
1.3 KiB
Python
44 lines
1.3 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 rp2pio
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import board
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import time
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import adafruit_pioasm
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import digitalio
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# NeoPixels are 800khz bit streams. Zeroes are 1/3 duty cycle (~416ns) and ones
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# are 2/3 duty cycle (~833ns).
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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 [1]; Side-set still takes place when instruction stalls
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jmp !x do_zero side 1 [1]; Branch on the bit we shifted out. Positive pulse
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do_one:
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jmp bitloop side 1 [1]; Continue driving high, for a long pulse
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do_zero:
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nop side 0 [1]; Or drive low, for a short pulse
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.wrap
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"""
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assembled = adafruit_pioasm.assemble(program)
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sm = rp2pio.StateMachine(assembled,
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frequency=800000 * 6, # 800khz * 6 clocks per bit
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init=adafruit_pioasm.assemble("set pindirs 1"),
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first_set_pin=board.D12,
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first_sideset_pin=board.D12,
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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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print("real frequency", sm.frequency)
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for i in range(100):
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sm.write(b"\x0a\x00\x00")
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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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