pimoroni-pico/drivers/plasma/ws2812.pio

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;
; Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
;
; SPDX-License-Identifier: BSD-3-Clause
;
.program ws2812
.side_set 1
.define public T1 2
.define public T2 5
.define public T3 3
.lang_opt python sideset_init = pico.PIO.OUT_HIGH
.lang_opt python out_init = pico.PIO.OUT_HIGH
.lang_opt python out_shiftdir = 1
.wrap_target
bitloop:
out x, 1 side 0 [T3 - 1] ; Side-set still takes place when instruction stalls
jmp !x do_zero side 1 [T1 - 1] ; Branch on the bit we shifted out. Positive pulse
do_one:
jmp bitloop side 1 [T2 - 1] ; Continue driving high, for a long pulse
do_zero:
nop side 0 [T2 - 1] ; Or drive low, for a short pulse
.wrap