Methods and apparatus, including computer program products, are provided for wireless charging. In some example embodiments, there is provide a method. The method may include receiving, at a power receiver, a first ping message and a second ping message; detecting, at the power receiver, a first time between transmissions of the first ping message and the second ping message; and decoding, at the power receiver, the first time into a data value representative of a transmitted data value sent by a power transmitter. Related apparatus, systems, methods, and articles are also described.