Uplink and downlink CayenneLPP payload to TTN using LMIC library

[shramik_salgaonkar]

@shramik_salgaonkar

    lpp.addTemperature(1, 123));
    lpp.addAnalogInput(4, 123);

to create a button you need to send the correct data type. For button it will be lpp.addDigitalInput(1,0) where 1 is the channel and 0 is the one time data. once done you can read the button status with decoding the above downlink format