Reading DHT22 sensor with NodeMCU

I'm trying to read temperature data from a DHT22 using NodeMCU. This is my script:

function GetSensorData()
    print( "Trying to get temperature..." )
    pin = 4
    status, temp, humi, temp_dec, humi_dec = dht.read(pin)
    if status == dht.OK then
        print("DHT Temperature:"..temp..";".."Humidity:"..humi)
    elseif status == dht.ERROR_CHECKSUM then
        print( "DHT Checksum error." )
    elseif status == dht.ERROR_TIMEOUT then
        print( "DHT timed out." )
    end
end

-- MAIN
tmr.alarm(1, 1000, 1, function() GetSensorData() end)

This gives me the following output (over and over):

Trying to get temperature... DHT timed out. ....

I tried every possible value for "pin", and attached the DHT22 data output to all GPIOs of my NodeMCU.

The pins are connected like this:

DHT22-VCC -> NodeMCU-3.3V
DHT22-GND -> NodeMCU-GND
DHT22-DATA -> NodeMCU-D0, D1, D2, D3, D4 (tried em all)

I've run out oif ideas. What could be the problem here?

Solution

Ok, here we go...

Pin numbers must be mapped from what it says on the module to an index that you use in Lua code. See https://nodemcu.readthedocs.org/en/dev/en/modules/gpio. For example with pin = 4 you'd have to use GPIO2 on the module.