I have fabricated a wifi temperature sensor for my IoT project, IoT Plan.
The sensor board uses an ESP32 module for its core functionality: controller, wifi and temperature sensor. I paired it with a buck-boost voltage regulator that can be supplied by battery (3V) or micro-usb (5V) source. A 4-bit device Id can be configured using jumpers on GPIO pins. The intent is to use the ESP32 module's temperature sensor, however there is on-board support a for a DB18B20 temperature sensor. The circuit diagram follows. I had 9 blank boards fabricated by external link OSH Park, and I will assemble the boards by hand. The first, as yet un-tested, board is pictured below. The next steps is to verfy that assembly was successful and that the board functions. I have already written initial firmware and look forward to seeing if it works.