klipper/src/neopixel.c

// Support for bit-banging commands to WS2812 type "neopixel" LEDs
//
// Copyright (C) 2019  Kevin O'Connor <kevin@koconnor.net>
//
// This file may be distributed under the terms of the GNU GPLv3 license.

#include "autoconf.h" // CONFIG_MACH_AVR
#include "board/gpio.h" // gpio_out_write
#include "board/irq.h" // irq_poll
#include "board/misc.h" // timer_read_time
#include "basecmd.h" // oid_alloc
#include "command.h" // DECL_COMMAND

struct neopixel_s {
    struct gpio_out pin;
    uint32_t last_req_time;
};

void
command_config_neopixel(uint32_t *args)
{
    struct gpio_out pin = gpio_out_setup(args[1], 0);
    struct neopixel_s *n = oid_alloc(args[0], command_config_neopixel
                                     , sizeof(*n));
    n->pin = pin;
}
#if !CONFIG_MACH_AVR
DECL_COMMAND(command_config_neopixel, "config_neopixel oid=%c pin=%u");
#endif

uint32_t
timer_from_ns(uint32_t ns)
{
    return timer_from_us(ns * 1000) / 1000000;
}

static int
send_data(struct neopixel_s *n, uint32_t data)
{
    // Make sure at least 50us has passed since last request
    uint32_t last_req_time = n->last_req_time, cur = timer_read_time();
    while (cur - last_req_time < timer_from_us(50)) {
        irq_poll();
        cur = timer_read_time();
    }

    struct gpio_out pin = n->pin;
    uint32_t expire_time = cur + 0x40000000;
    uint_fast8_t bits = 24;
    while (bits--) {
        // Calculate pulse duration
        uint32_t on, off;
        if (data & 0x800000) {
            on = timer_from_ns(700 - 150);
            off = timer_from_ns(600 - 150);
        } else {
            on = timer_from_ns(350 - 150);
            off = timer_from_ns(800 - 150);
        }
        data <<= 1;

        // Set output high
        gpio_out_write(pin, 1);
        uint32_t on_start_time = timer_read_time();
        if (timer_is_before(expire_time, on_start_time))
            goto fail;
        cur = on_start_time;
        while (timer_is_before(cur, on_start_time + on)) {
            irq_poll();
            cur = timer_read_time();
        }

        // Set output low
        gpio_out_write(pin, 0);
        uint32_t off_start_time = timer_read_time();
        expire_time = on_start_time + on + timer_from_ns(300);
        if (timer_is_before(expire_time, off_start_time))
            goto fail;
        cur = off_start_time;
        while (timer_is_before(cur, off_start_time + off)) {
            irq_poll();
            cur = timer_read_time();
        }
        expire_time = off_start_time + off + timer_from_ns(300);
    }
    n->last_req_time = cur;
    return 0;
fail:
    // A hardware irq messed up the transmission - report a failure
    n->last_req_time = cur;
    return -1;
}

void
command_neopixel_send(uint32_t *args)
{
    uint8_t oid = args[0];
    struct neopixel_s *n = oid_lookup(oid, command_config_neopixel);
    uint32_t data = args[1];

    uint_fast8_t retry = 8;
    while (retry--) {
        int ret = send_data(n, data);
        if (!ret)
            break;
    }
}
#if !CONFIG_MACH_AVR
DECL_COMMAND(command_neopixel_send, "neopixel_send oid=%c data=%u");
#endif