Anyone who’s ever slept through a morning’s alarm can tell you that sounds, even loud piercing ones, don’t always wake a person out of a deep sleep. Similarly, hearing a baby cry on the other side of the monitor might not always wake a parent up in the middle of the night. So what’s the solution? This haptic baby monitor created by [Guy Dupont] certainly looks like it has some promise.
[Guy] picked up a fairly standard baby monitor from VTech and popped it open to see how he could tie a vibration motor into the original circuitry. He originally thought he’d have to do some signal processing magic to figure out the amplitude of the audio, but then he realized that the five LEDs on the front of the unit that light up to indicate the audio level were already doing the hard work for him.
So he wired each of the LEDs up to the pins of a Seeed Studio XIAO nRF52840 microcontroller, and wrote some code that would poll their status a few hundred times per second. Dividing the total number of LEDs by the count of how many are currently illuminated gives him a nice average that he can use to set the intensity of the vibration motor that he’s built into a stretchy armband.
For extra points, [Guy] is also using the Bluetooth capability of the XIAO to provide a rudimentary configuration service — just connect up to the MCU with a Bluetooth serial application on your computer or phone, and fire off a value between 0 and 10 to augment the motor’s intensity. There’s also a BLE characteristic which can be read from a client device to determine the currently detected audio amplitude, which could be used to chart how well the baby is sleeping over time. Alternately, as demonstrated at the end of the video, you could use it to play Flappy Bird.
It’s an elegant modification that could potentially hold promise for parent’s who need a bit of extra help keeping tabs on their miniature humans. This isn’t the first time we’ve seen hackers try to improve upon the classic baby monitor, but this is arguably the most approachable attempt we’ve seen to date.