Waveshare RP2040-Zero C sample code

CMakeLists.txt

# Generated Cmake Pico project file

cmake_minimum_required(VERSION 3.13)

set(CMAKE_C_STANDARD 11)
set(CMAKE_CXX_STANDARD 17)

# initalize pico_sdk from installed location
# (note this can come from environment, CMake cache etc)
#set(PICO_SDK_PATH "D:/Raspberry/Pico-Code/pico-sdk")

# Pull in Raspberry Pi Pico SDK (must be before project)
include(pico_sdk_import.cmake)

project(RP2040_Zero_Test C CXX ASM)

# Initialise the Raspberry Pi Pico SDK
pico_sdk_init()

# Add executable. Default name is the project name, version 0.1

add_executable(RP2040_Zero_Test RP2040_Zero_Test.c )

pico_generate_pio_header(RP2040_Zero_Test ${CMAKE_CURRENT_LIST_DIR}/ws2812.pio OUTPUT_DIR ${CMAKE_CURRENT_LIST_DIR}/generated)

pico_set_program_name(RP2040_Zero_Test "RP2040_Zero_Test")
pico_set_program_version(RP2040_Zero_Test "0.1")

pico_enable_stdio_uart(RP2040_Zero_Test 0)
pico_enable_stdio_usb(RP2040_Zero_Test 0)

# Add the standard library to the build
target_link_libraries(RP2040_Zero_Test pico_stdlib)

# Add any user requested libraries
target_link_libraries(RP2040_Zero_Test
        hardware_pio
        )

pico_add_extra_outputs(RP2040_Zero_Test)

RP2040_Zero_Test.c

#include <stdio.h>
#include <stdlib.h>

#include "pico/stdlib.h"
#include "hardware/pio.h"
#include "hardware/clocks.h"
#include "ws2812.pio.h"

void put_pixel(uint32_t pixel_grb)
{
    pio_sm_put_blocking(pio0, 0, pixel_grb << 8u);
}
void put_rgb(uint8_t red, uint8_t green, uint8_t blue)
{
    uint32_t mask = (green << 16) | (red << 8) | (blue << 0);
    put_pixel(mask);
}

int main()
{
    //set_sys_clock_48();
    stdio_init_all();

    PIO pio = pio0;
    int sm = 0;
    uint offset = pio_add_program(pio, &ws2812_program);
    uint8_t cnt = 0;

    puts("RP2040-Zero WS2812 Test");

    ws2812_program_init(pio, sm, offset, 16, 800000, true);

    while (1)
    {
        for (cnt = 0; cnt < 0xff; cnt++)
        {
            put_rgb(cnt, 0xff - cnt, 0);
            sleep_ms(3);
        }
        for (cnt = 0; cnt < 0xff; cnt++)
        {
            put_rgb(0xff - cnt, 0, cnt);
            sleep_ms(3);
        }
        for (cnt = 0; cnt < 0xff; cnt++)
        {
            put_rgb(0, cnt, 0xff - cnt);
            sleep_ms(3);
        }
    }
}

ws2812.pio

;
; Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
;
; SPDX-License-Identifier: BSD-3-Clause
;
.pio_version 0 // only requires PIO version 0

.program ws2812
.side_set 1

; The following constants are selected for broad compatibility with WS2812,
; WS2812B, and SK6812 LEDs. Other constants may support higher bandwidths for
; specific LEDs, such as (7,10,8) for WS2812B LEDs.

.define public T1 3
.define public T2 3
.define public T3 4

.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 3
.define public T2 3
.define public T3 4

.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_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);
}
%}

I do not remember where I got this link from - https://www.waveshare.com/w/upload/5/58/RP2040-Zero.zip it is definitely not from their wiki.

posting the relevant code here in case i need to refer later. My rp2040-blinky is based on this sample code