luaCanRxWorkaround¶

By default Lua CAN RX is easy but has a performance limitation.

If 300hz and above Lua CAN RX is needed we have the luaCanRxWorkaround magic option until a more elegant solution is implemented.

For the magic to work, two lines are required in the Lua script:

global_can_data = { } at the beginning of the script

and at least one global_can_data[1] read access to global_can_data anywhere in the script.

rxCount = 0

-- magic behind the scenes: luaCanRxWorkaround on ParkingLot2 dialog
global_can_data = { }

function onVehicleDetect(bus, id, dlc, data)
    rxCount = rxCount + 1
    if rxCount < 10 then
-- at least one read from global_can_data to prevent garbage collection
        print('onVehicleDetect ' ..id .." " ..global_can_data[1])

    end
end

canRxAddMask(0, 0xFFFFFF00, onVehicleDetect)

everySecondTimer = Timer.new()
keepAlive = 0

function onTick()
    if everySecondTimer : getElapsedSeconds() > 1 then
        everySecondTimer : reset()
        keepAlive = keepAlive + 1
        print("Alive seconds=" ..keepAlive .. " rxCount " .. rxCount )
    end
end

Gives us:

2024-02-25_09_12_32_236: EngineState: LUA: Alive seconds=4 rxCount 596
2024-02-25_09_12_33_240: EngineState: LUA: Alive seconds=5 rxCount 912
2024-02-25_09_12_34_352: EngineState: LUA: Alive seconds=6 rxCount 1166
2024-02-25_09_12_35_357: EngineState: LUA: Alive seconds=7 rxCount 1420
2024-02-25_09_12_36_467: EngineState: LUA: Alive seconds=8 rxCount 1775
2024-02-25_09_12_37_577: EngineState: LUA: Alive seconds=9 rxCount 2030
2024-02-25_09_12_38_577: EngineState: LUA: Alive seconds=10 rxCount 2280
2024-02-25_09_12_39_582: EngineState: LUA: Alive seconds=11 rxCount 2605
2024-02-25_09_12_40_588: EngineState: LUA: Alive seconds=12 rxCount 2851
2024-02-25_09_12_41_592: EngineState: LUA: Alive seconds=13 rxCount 3076