WR703N + OpenWRT cat feeder

controller.lua

-- lucidir/controller/cats.lua
module("luci.controller.cats", package.seeall)

function index()
    entry({"cats"}, cbi("cats"), "Feed cats", 30).dependent=false
end

model.lua

-- lucidir/model/cbi/cats.lua
f = SimpleForm("cats", "Feed cats")
f.submit = false
f.reset = false
f:field(Value, "time", translate("Time in seconds"))
f:field(Button, "_btn", translate("Click to feed"))

function f.handle(self, state, data)
    time = tonumber(data.time)
    -- If all mandatory fields are filled and module should be enabled
    if state == FORM_VALID and time and time > 0 then

        -- Check for parameters and append them if set
        command = "echo '1' > /sys/class/gpio/gpio29/value && sleep %s && echo '0' > /sys/class/gpio/gpio29/value" % { time }

        -- Execute and save return code
        local stat = luci.sys.call(command)

        -- Check whether action succeeded (return code: 0)
        if stat == 0 then
            f.message = "Ran %s seconds" % { time }
        else
            f.errmessage = "Failed. Code: %i" % stat
        end
    end
end

-- Return form
return f