/**
 * Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

#include <stdio.h>

#include "pico/stdlib.h"
#include "hardware/pio.h"
#include "hardware/clocks.h"
#include "blink.pio.h"

void blink_pin_forever(PIO pio, uint sm, uint offset, uint pin, uint freq);

int main() {
//    setup_default_uart();

    // todo get free sm
    PIO pio = pio0;
    uint offset = pio_add_program(pio, &blink_program);
    printf("Loaded program at %d\n", offset);

    blink_pin_forever(pio, 0, offset, 0, 3);
    blink_pin_forever(pio, 1, offset, 1, 4);
    blink_pin_forever(pio, 2, offset, 2, 1);
  while (true) {
  }
}

void blink_pin_forever(PIO pio, uint sm, uint offset, uint pin, uint freq) {
    blink_program_init(pio, sm, offset, pin);
    pio_sm_set_enabled(pio, sm, true);

    printf("Blinking pin %d at %d Hz\n", pin, freq);

    // PIO counter program takes 3 more cycles in total than we pass as
    // input (wait for n + 1; mov; jmp)
    pio->txf[sm] = (clock_get_hz(clk_sys) / (2 * freq)) - 3;
}

main.c

diagram.json

// -------------------------------------------------- //
// This file is autogenerated by pioasm; do not edit! //
// -------------------------------------------------- //

#pragma once

#if !PICO_NO_HARDWARE
#include "hardware/pio.h"
#endif

// ----- //
// blink //
// ----- //

#define blink_wrap_target 2
#define blink_wrap 7

static const uint16_t blink_program_instructions[] = {
    0x80a0, //  0: pull   block                      
    0x6040, //  1: out    y, 32                      
            //     .wrap_target
    0xa022, //  2: mov    x, y                       
    0xe001, //  3: set    pins, 1                    
    0x0044, //  4: jmp    x--, 4                     
    0xa022, //  5: mov    x, y                       
    0xe000, //  6: set    pins, 0                    
    0x0047, //  7: jmp    x--, 7                     
            //     .wrap
};

#if !PICO_NO_HARDWARE
static const struct pio_program blink_program = {
    .instructions = blink_program_instructions,
    .length = 8,
    .origin = -1,
};

static inline pio_sm_config blink_program_get_default_config(uint offset) {
    pio_sm_config c = pio_get_default_sm_config();
    sm_config_set_wrap(&c, offset + blink_wrap_target, offset + blink_wrap);
    return c;
}

// this is a raw helper function for use by the user which sets up the GPIO output, and configures the SM to output on a particular pin
void blink_program_init(PIO pio, uint sm, uint offset, uint pin) {
   pio_sm_config c = blink_program_get_default_config(offset);
   pio_gpio_init(pio, pin);
   pio_sm_set_consecutive_pindirs(pio, sm, pin, 1, true);
   //pio_sm_config c = blink_program_get_default_config(offset);
   sm_config_set_set_pins(&c, pin, 1);
   pio_sm_init(pio, sm, offset, &c);
}

#endif

blink.pio.h

;
; Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
;
; SPDX-License-Identifier: BSD-3-Clause
;
; 
; SET pin 0 should be mapped to your LED GPIO

;https://wokwi.com/tools/pioasm


.program blink
    pull block
    out y, 32
.wrap_target
    mov x, y
    set pins, 1   ; Turn LED on
lp1:
    jmp x-- lp1   ; Delay for (x + 1) cycles, x is a 32 bit number
    mov x, y
    set pins, 0   ; Turn LED off
lp2:
    jmp x-- lp2   ; Delay for the same number of cycles again
.wrap             ; Blink forever!


% c-sdk {
// this is a raw helper function for use by the user which sets up the GPIO output, and configures the SM to output on a particular pin

void blink_program_init(PIO pio, uint sm, uint offset, uint pin) {
   pio_gpio_init(pio, pin);
   pio_sm_set_consecutive_pindirs(pio, sm, pin, 1, true);
   pio_sm_config c = blink_program_get_default_config(offset);
   sm_config_set_set_pins(&c, pin, 1);
   pio_sm_init(pio, sm, offset, &c);
}
%}