44 lines
1.3 KiB
Plaintext
44 lines
1.3 KiB
Plaintext
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; --------------------------------------------------
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; Quadrature Output using PIO
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; by Christopher (@ZodiusInfuser) Parrott
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; --------------------------------------------------
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;
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; A simple PIO that will create a quadrature output signal
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; for use with testing quadrature decoder code
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; Constants
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; --------------------------------------------------
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.define public QUAD_OUT_SET_CYCLES 10
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.program quadrature_out
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.wrap_target
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set pins, 0 [QUAD_OUT_SET_CYCLES - 1]
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set pins, 1 [QUAD_OUT_SET_CYCLES - 1]
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set pins, 3 [QUAD_OUT_SET_CYCLES - 1]
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set pins, 2 [QUAD_OUT_SET_CYCLES - 1]
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.wrap
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; Initialisation Code
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; --------------------------------------------------
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% c-sdk {
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#include "hardware/clocks.h"
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void quadrature_out_program_init(PIO pio, uint sm, uint offset, uint pin, float freq)
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{
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pio_gpio_init(pio, pin);
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pio_gpio_init(pio, pin + 1);
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pio_sm_set_consecutive_pindirs(pio, sm, pin, 2, true);
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pio_sm_config c = quadrature_out_program_get_default_config(offset);
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sm_config_set_set_pins(&c, pin, 2);
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int cycles_per_bit = QUAD_OUT_SET_CYCLES * 4;
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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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