As promised in the last post, here’s a look under the hood of how the Sparrowscope works. The motors are controlled by a smart phone, but of course smart phones don’t have motor outputs. So how will this work?
The smart phone will communicate with some intermediary electronics, which in turn will drive the motor. And of course, the standard connector across all phones is… the headphone jack! I didn’t want to limit devices to only an Apple connector (and then it’s a pick between Lightning and the older 30-pin connector), or USB for Android devices. Bluetooth has too much of a delay and would make the Sparrowscope more expensive and less easy to experiment with. So that’s why the Sparrowscope is going to use sounds over a headphone cord to communicate. By playing different tones, the smart phone will tell the circuitry how much to pan and tilt.
Here’s a video I took when I was testing the frequency measuring code for the first time:
I’ll go into more detail on the communication protocol in the coming months, so that it’s completely open as to what tones will control the Sparrowscope. It will be possible for tinkerers to easily make the Sparrowscope do what they want it to—anyone could make and share their own app. Maybe you’d like a more complex control loop, using the compass in your phone to aim the camera by heading angle? A panorama-making app? You could even send up something other than a smart phone. Maybe lift an aerial Raspberry Pi? I’m exited to see all the creative things people do with their Sparrowscopes!