A smart-home device may include a user interface having a first operating mode and a second operating mode, and a four-channel thermopile. A processing system may be programmed to receive an indication of a user presence near the smart-home device from the thermopile, and determine a motion signature based on the responses from the thermopile. The processing system may also be programmed to process the determined motion signature to determine the presence of a condition warranting user interface entry into the first mode from the second mode, and cause the user interface to transition from the first mode to the second mode based on the determined motion signature.