52 lines
1.3 KiB
C
52 lines
1.3 KiB
C
/**
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* Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
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*
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* SPDX-License-Identifier: BSD-3-Clause
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*/
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#include <stdio.h>
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#include "pico/stdlib.h"
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#include "hardware/pio.h"
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#include "pwm.pio.h"
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// Write `period` to the input shift register
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void pio_pwm_set_period(PIO pio, uint sm, uint32_t period) {
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pio_sm_set_enabled(pio, sm, false);
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pio_sm_put_blocking(pio, sm, period);
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pio_sm_exec(pio, sm, pio_encode_pull(false, false));
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pio_sm_exec(pio, sm, pio_encode_out(pio_isr, 32));
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pio_sm_set_enabled(pio, sm, true);
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}
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// Write `level` to TX FIFO. State machine will copy this into X.
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void pio_pwm_set_level(PIO pio, uint sm, uint32_t level) {
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pio_sm_put_blocking(pio, sm, level);
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}
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int main() {
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stdio_init_all();
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#ifndef PICO_DEFAULT_LED_PIN
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#warning pio/pwm example requires a board with a regular LED
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puts("Default LED pin was not defined");
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#else
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// todo get free sm
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PIO pio = pio0;
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int sm = 0;
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uint offset = pio_add_program(pio, &pwm_program);
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printf("Loaded program at %d\n", offset);
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pwm_program_init(pio, sm, offset, PICO_DEFAULT_LED_PIN);
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pio_pwm_set_period(pio, sm, (1u << 16) - 1);
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int level = 0;
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while (true) {
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printf("Level = %d\n", level);
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pio_pwm_set_level(pio, sm, level * level);
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level = (level + 1) % 256;
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sleep_ms(10);
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}
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#endif
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}
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