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// 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
gpio_out_write(pin, 0);
n->last_req_time = timer_read_time();
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
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