How to get current time inside Lua script?

ArduPilot Lua Scripting
1

Hello community!
I want to get current time(os.time()) and set is as parameter by using Ardupilot
Here is my pseudo-code:
– Load MAVLink library
mavlink = require(“mavlink”)

– Function to set a parameter using MAVLink
function setParameter(param_id, value)
local msg = mavlink.messages.param_set_encode(
system_id, – Your system ID
component_id, – Your component ID
param_id,
value,
mavlink.MAV_PARAM_TYPE_REAL32
)
mavlink.send_message(msg)
end

– Calculate current time in seconds since epoch
local currentTime = os.time()

– Set the “CurrentTime” parameter in ArduPilot
setParameter(“CurrentTime”, currentTime)

Please give me a tip how to do it properly

3

Your method of setting a parameter is incorrect (and probably misled, since a parameter with the current time is rather strange…).

See here for the proper way to initiate a custom parameter via Lua.

The following series of functions and snippets may prove useful regarding real-world time calculations in ArduPilot Lua. Note, I have not thoroughly tested any of it, but it seems to work ok in SITL.

-- ported to Lua from https://gwosc.org/static/js/gpstimeutil.js
-- Yuri - Oct 2023

local LOCAL_TIMEZONE_OFFSET = -5

local MONTH_NAMES = { 'Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun',
                      'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec' }

local LEAP_SECONDS = { 46828800, 78364801, 109900802, 173059203, 252028804,
    315187205, 346723206, 393984007, 425520008, 457056009, 504489610,
    551750411, 599184012, 820108813, 914803214, 1025136015, 1119744016,
    1167264017 }

-- test to see if a GPS second is a leap second
local function isleap(gpsTimeSeconds)
    for _, leap in ipairs(LEAP_SECONDS) do
        if (gpsTimeSeconds == leap) then return true end
    end
    return false
end

-- count number of leap seconds that have passed
local function countleaps(gpsTimeSeconds, accum_leaps)
    local nleaps = 0

    if (accum_leaps) then
        for i, leap in ipairs(LEAP_SECONDS) do
            if (gpsTimeSeconds + i - 1 >= leap) then
                nleaps = nleaps + 1
            end
        end
    else
        for _, leap in ipairs(LEAP_SECONDS) do
            if (gpsTimeSeconds >= leap) then
                nleaps = nleaps + 1
            end
        end
    end
    return nleaps
end

-- convert GPS Time to Unix Time
local function gps2unix(gpsTimeSeconds)
    local fpart = gpsTimeSeconds % 1
    local ipart = math.floor(gpsTimeSeconds)
    local unixTimeSeconds = ipart + 315964800 - countleaps(ipart, false)

    if isleap(ipart + 1) then
        unixTimeSeconds = unixTimeSeconds + fpart / 2
    elseif isleap(ipart) then
        unixTimeSeconds = unixTimeSeconds + (fpart + 1) / 2
    else
        unixTimeSeconds = unixTimeSeconds + fpart
    end
    return unixTimeSeconds
end

local function unix2str(unixTimeSeconds, tz_offset)
    local epoch = 946684800 -- January 1, 2000, 00:00:00 (UTC)
    local secondsInDay = 86400
    local offset = tz_offset or 0  -- default to UTC if tz_offset not specified
    unixTimeSeconds = unixTimeSeconds + offset * 3600

    local days = math.floor((unixTimeSeconds - epoch) / secondsInDay)
    local secondsLeft = (unixTimeSeconds - epoch) % secondsInDay

    local year = 2000
    local month, day = 1, 1

    while true do
        local daysInMonth = 31

        if month == 4 or month == 6 or month == 9 or month == 11 then
            daysInMonth = 30
        elseif month == 2 then
            if year % 4 == 0 and (year % 100 ~= 0 or year % 400 == 0) then
                daysInMonth = 29
            else
                daysInMonth = 28
            end
        end

        if days >= daysInMonth then
            days = days - daysInMonth
            month = month + 1
        else
            day = days + 1
            break
        end

        if month > 12 then
            month = 1
            year = year + 1
        end
    end

    local hours = math.floor(secondsLeft / 3600)
    local minutes = math.floor((secondsLeft % 3600) / 60)
    local seconds = secondsLeft % 60

    local tz = 'UTC'
    if offset > 0 then tz = ('%s+%.1f'):format(tz, offset) end
    if offset < 0 then tz = ('%s%.1f'):format(tz, offset) end

    return ('%02d %s %04d %02d:%02d:%02d %s'):format(day, MONTH_NAMES[month], year, hours, minutes, seconds, tz)
end

local function getGpsTimeSeconds() -- in seconds
    local SECONDS_IN_WEEK = 604800
    return gps:time_week(0) * SECONDS_IN_WEEK + tonumber(tostring(gps:time_week_ms(0))) / 1000
end

function update()
    local utc = gps2unix(getGpsTimeSeconds())
    gcs:send_text(6, unix2str(utc))
    gcs:send_text(6, unix2str(utc, LOCAL_TIMEZONE_OFFSET))
    return update, 1000
end

return update()
1 Like
4

Yuri_Rage thank you for a help!