Stationary bikes are a great way to exercise and keep cycling when the weather outside is less than ideal. But biking outside is inherently interesting, because you’re moving dynamically and get to experience all the sights and scents of nature around you. Cycling indoors on a stationary bike can get pretty dull, which is why you’ll probably won’t some motivation to keep it up. Watching TV while you cycle is one option, but how do you keep yourself pedaling when you become engrossed in a show? Imgurian VGCProjects’ solution was to use an Adafruit Feather nRF52 to turn off Netflix if they don’t pedal fast enough.
VGCProjects started this build after the computer built into their exercise bike stopped working. They wanted a way to bring back the original functionality of tracking speed and miles, and decided to add the Netflix motivation feature while they were at it. To do that, they placed a Hall effect sensor on the stationary bike with a magnet on one of the pedals. An Adafruit Feather nRF52 BLE (Bluetooth Low Energy) development board is used to monitor the Hall effect sensor. Whenever the pedal passes by the sensor, it counts that as a single revolution. Some simple math can then be used to extrapolate the current pedaling speed.
The Adafruit Feather nRF52 then connects to VGCProjects’ computer and shows up as a Bluetooth keyboard. If their pedaling speed falls below the goal speed, the Feather nRF52 sends “ALT+F4” key presses to the computer, forcing it to exit out of Netflix. VGCProjects can also send the tracked speed and mileage data to the computer by pushing a button on the Feather nRF52’s enclosure. Doing so sends a sequence of key presses that write out the logged data into a simple text editor. The Adafruit Feather nRF52 is just $25, and you can often find used stationary bikes for very low prices. That makes this an affordable project if you want to have a great indoor cycling experience.