-- Watchdog-like "~X" protocol parser built on top of cmd.
-- Each incoming frame must be terminated by CR or LF because cmd is line-based.
--
-- Implemented subset:
--   ~U           -> ~A, green blink, timer reset, escalation reset
--   ~I           -> firmware/version text
--   ~G           -> temperature reply in "~Gxxxx" format
--

local TIMER_MAX = 5000
local TIMER_DELTA = 50
local RESET_TIME = 200
local POWER_OFF_T1 = 5000
local POWER_OFF_DELAY = 3000
local POWER_OFF_T2 = 200

local RESET_PIN = hw.pa3
local POWER_PIN = hw.pa2
local TEMP_PIN = hw.p9

local GREEN_BLINK_MS = 120
local RED_BLINK_ON_MS = 120
local RED_STEADY_MS = 400

local VERSION_TEXT = "ARU-P2 watchdog uLua"

local STAGE_RESET = 0
local STAGE_POWER = 1

function write_error()
    cmd.write("~E\n")
end

function pulse(pin, ms)
    hw.gpio_set(pin, 1)
    hw.delay_ms(ms)
    hw.gpio_set(pin, 0)
end

function fmt_dec4(value)
    if value < 0 then
        value = 0
    elseif value > 9999 then
        value = 9999
    end

    if value < 100 then
        if value < 10 then
            return "000" .. value
        end
        return "00" .. value
    end
    if value < 1000 then
        return "0" .. value
    end
    return "" .. value
end

hw.gpio_init(RESET_PIN, hw.out)
hw.gpio_init(POWER_PIN, hw.out)
hw.gpio_set(RESET_PIN, 0)
hw.gpio_set(POWER_PIN, 0)
hw.gpio_init(TEMP_PIN, hw.dht22)

cmd.echo(false)
hw.gled(false)
hw.rled(false)

local escalation_stage = STAGE_RESET
local timer_ms = TIMER_MAX
local green_ms = 0
local red_phase_ms = 0

while true do
    if cmd.begin() then
        if cmd.word("~U") then
            if cmd.done() then
                escalation_stage = STAGE_RESET
                timer_ms = TIMER_MAX
                red_phase_ms = 0
                green_ms = GREEN_BLINK_MS
                hw.gled(true)
                hw.rled(false)
                cmd.write("~A\n")
            else
                write_error()
            end

        elseif cmd.word("~I") then
            if cmd.done() then
                cmd.write(VERSION_TEXT .. "\n")
            else
                write_error()
            end

        elseif cmd.word("~G") then
            if cmd.done() then
                local temp_x10 = hw.dht_temp(TEMP_PIN)
                cmd.write("~G" .. fmt_dec4(temp_x10) .. "\n")
            else
                write_error()
            end

        else
            cmd.done()
            write_error()
        end
    end

    if green_ms > 0 then
        green_ms = green_ms - TIMER_DELTA
        if green_ms <= 0 then
            green_ms = 0
            hw.gled(false)
        end
    end

    local red_interval = 0
    if timer_ms > RED_STEADY_MS then
        red_interval = 300 + (2700 * timer_ms) / TIMER_MAX
    end

    if red_interval == 0 then
        hw.rled(true)
    else
        red_phase_ms = red_phase_ms + TIMER_DELTA
        if red_phase_ms >= red_interval then
            red_phase_ms = 0
        end

        if red_phase_ms < RED_BLINK_ON_MS then
            hw.rled(true)
        else
            hw.rled(false)
        end
    end

    hw.delay_ms(TIMER_DELTA)

    timer_ms = timer_ms - TIMER_DELTA
    if timer_ms <= 0 then
        hw.rled(true)

        if escalation_stage == STAGE_RESET then
            pulse(RESET_PIN, RESET_TIME)
            escalation_stage = STAGE_POWER
        else
            pulse(POWER_PIN, POWER_OFF_T1)
            hw.delay_ms(POWER_OFF_DELAY)
            pulse(POWER_PIN, POWER_OFF_T2)
        end

        timer_ms = TIMER_MAX
        red_phase_ms = 0
        hw.rled(false)
    end
end

hw.gpio_init(pin, mode)
Устанавливает режим hw.inp, hw.out, hw.pwm, hw.adc, hw.capture и т.д.
hw.gpio_init(hw.p1, hw.out)

hw.gpio_set(pin, value)
Устанавливает логический уровень 0 или 1.
hw.gpio_set(hw.p1, 1)

hw.gpio_get(pin) -> int
Читает уровень 0 или 1.
local level = hw.gpio_get(hw.p1)

hw.gpio_init(hw.p5, hw.adc)
local v = hw.adc_read(hw.p5)

hw.pwm_init(pin, frequency_hz)
Инициализирует PWM на заданной частоте.

hw.pwm_set(pin, duty_percent)
Устанавливает duty cycle 0..100.

Пример:
hw.gpio_init(hw.p3, hw.pwm)
hw.pwm_init(hw.p3, 1000)
hw.pwm_set(hw.p3, 50)

DHT22
hw.dht_temp(pin) -> int
Температура в десятых долях градуса Цельсия.

hw.dht_hum(pin) -> int
Влажность в десятых долях процента.

hw.gpio_init(hw.p1, hw.dht22)
local t = hw.dht_temp(hw.p1)
local h = hw.dht_hum(hw.p1)

hw.delay_ms(ms)
Задержка в миллисекундах.

hw.uptime() -> int
Секунды с момента старта устройства.

hw.now() -> int
Миллисекунды с момента старта устройства.

hw.timer_after(ms, func[, arg1[, arg2]]) -> int
Однократный запуск таймера через ms.

hw.timer_every(ms, func[, arg1[, arg2]]) -> int
Периодический запуск таймера через ms.

hw.timer_cancel(timer_id)
Отмена таймера.

hw.rled(on)
Управляет красным светодиодом.

hw.gled(on)
Управляет зелёным светодиодом.

Пример:
hw.rled(true)
hw.gled(false)