If somebody rings your doorbell and you’re not at home to hear it, does it make a sound? Adrian Fernandez at Texas Instruments built himself an IoT doorbell to render the question moot. Adrian wanted a way to know if someone happened to be looking for him while he was away from his desk, so he designed a simple doorbell that calls his phone whenever someone presses it. When he gets the phone call, he can then indicate whether or not he’ll be back soon by entering a number into his phone’s keypad, and a corresponding happy or sad face will be displayed on the doorbell. He used an MSP432 LaunchPad board with a CC3100 WiFi shield and Temboo’s Nexmo Choreos to make it all work.