2023-01-01 16:47:30 +01:00
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.program ws2812
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2023-01-01 21:17:59 +01:00
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.side_set 1
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.define public T1 2
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.define public T2 5
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.define public T3 3
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.lang_opt python sideset_init = pico.PIO.OUT_HIGH
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.lang_opt python out_init = pico.PIO.OUT_HIGH
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.lang_opt python out_shiftdir = 1
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.wrap_target
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bitloop:
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out x, 1 side 0 [T3 - 1] ; Side-set still takes place when instruction stalls
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jmp !x do_zero side 1 [T1 - 1] ; Branch on the bit we shifted out. Positive pulse
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do_one:
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jmp bitloop side 1 [T2 - 1] ; Continue driving high, for a long pulse
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do_zero:
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nop side 0 [T2 - 1] ; Or drive low, for a short pulse
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.wrap
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% c-sdk {
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#include "hardware/clocks.h"
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static inline void ws2812_program_init(PIO pio, uint sm, uint offset, uint pin, float freq, bool rgbw) {
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pio_gpio_init(pio, pin);
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pio_sm_set_consecutive_pindirs(pio, sm, pin, 1, true);
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pio_sm_config c = ws2812_program_get_default_config(offset);
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sm_config_set_sideset_pins(&c, pin);
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sm_config_set_out_shift(&c, false, true, rgbw ? 32 : 24);
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sm_config_set_fifo_join(&c, PIO_FIFO_JOIN_TX);
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int cycles_per_bit = ws2812_T1 + ws2812_T2 + ws2812_T3;
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float div = clock_get_hz(clk_sys) / (freq * cycles_per_bit);
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sm_config_set_clkdiv(&c, div);
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pio_sm_init(pio, sm, offset, &c);
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pio_sm_set_enabled(pio, sm, true);
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}
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%}
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