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-rw-r--r--ws2812.pio85
1 files changed, 85 insertions, 0 deletions
diff --git a/ws2812.pio b/ws2812.pio
new file mode 100644
index 0000000..3c31fd6
--- /dev/null
+++ b/ws2812.pio
@@ -0,0 +1,85 @@
+;
+; 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
+
+% c-sdk {
+#include "hardware/clocks.h"
+
+static inline void ws2812_program_init(PIO pio, uint sm, uint offset, uint pin, float freq, bool rgbw) {
+
+ pio_gpio_init(pio, pin);
+ pio_sm_set_consecutive_pindirs(pio, sm, pin, 1, true);
+
+ pio_sm_config c = ws2812_program_get_default_config(offset);
+ sm_config_set_sideset_pins(&c, pin);
+ sm_config_set_out_shift(&c, false, true, rgbw ? 32 : 24);
+ sm_config_set_fifo_join(&c, PIO_FIFO_JOIN_TX);
+
+ int cycles_per_bit = ws2812_T1 + ws2812_T2 + ws2812_T3;
+ float div = clock_get_hz(clk_sys) / (freq * cycles_per_bit);
+ sm_config_set_clkdiv(&c, div);
+
+ pio_sm_init(pio, sm, offset, &c);
+ pio_sm_set_enabled(pio, sm, true);
+}
+%}
+
+.program ws2812_parallel
+
+.define public T1 2
+.define public T2 5
+.define public T3 3
+
+.wrap_target
+ out x, 32
+ mov pins, !null [T1-1]
+ mov pins, x [T2-1]
+ mov pins, null [T3-2]
+.wrap
+
+% c-sdk {
+#include "hardware/clocks.h"
+
+static inline void ws2812_parallel_program_init(PIO pio, uint sm, uint offset, uint pin_base, uint pin_count, float freq) {
+ for(uint i=pin_base; i<pin_base+pin_count; i++) {
+ pio_gpio_init(pio, i);
+ }
+ pio_sm_set_consecutive_pindirs(pio, sm, pin_base, pin_count, true);
+
+ pio_sm_config c = ws2812_parallel_program_get_default_config(offset);
+ sm_config_set_out_shift(&c, true, true, 32);
+ sm_config_set_out_pins(&c, pin_base, pin_count);
+ sm_config_set_set_pins(&c, pin_base, pin_count);
+ sm_config_set_fifo_join(&c, PIO_FIFO_JOIN_TX);
+
+ int cycles_per_bit = ws2812_parallel_T1 + ws2812_parallel_T2 + ws2812_parallel_T3;
+ float div = clock_get_hz(clk_sys) / (freq * cycles_per_bit);
+ sm_config_set_clkdiv(&c, div);
+
+ pio_sm_init(pio, sm, offset, &c);
+ pio_sm_set_enabled(pio, sm, true);
+}
+%}