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I’m diving into a project to create a tennis ball-sized squeeze ball that plays sounds when squeezed. I could really use your expertise in selecting the right components and designing the circuit. Here’s a quick rundown:
Goal: Make a small squeeze ball that generates sounds on a squeeze using a pressure sensor, microcontroller, and speaker/buzzer.
Yes, you are on the correct track. It’s been my experience that design is an iterative process. If your work follows the traditional path, you will first design a prototype that is large-and-simple. You will then build the project again using the lessons learned from the prototype. With each iteration your design becomes smaller and more complex.
Regarding your questions:
Are my component choices on the right track, or should I explore alternatives?
Recommend you place the microcontroller into a sleep mode to conserve battery life.
Assuming the ball is airtight, you could activate the song on a change of pressure as the ball is squeezed. For those unfamiliar with this technology, I recommend you start with an evaluation board.
An alternative is to use an accelerometer. Select accelerometers feature an interrupt output that may be used to signal the microcontroller to wake up.
How should I wire and connect these components for a small form factor?
Big-and-simple for the first iteration. A breadboard is appropriate. Once you have a working circuit you can then design a printed circuit board. This is not a complex process, but it will take time to develop these skills. There are many video tutorials online. As a starting point please consider:
What’s the best way to program the microcontroller to generate sounds on pressure changes?
As a starting point consider programming the Arduino to play the Super Mario Bros theme song. There are many examples online.
There are also microcontrollers capable of directly developing the sounds thereby elimination the need for an independent MP3 player. We can certainly explore these options in the future.
Tips for securing components inside the enclosure and achieving an airtight seal?
Sorry, that is outside of my wheelhouse.
Any vital components or considerations I might be missing?
As you move your project from big-and-simple to small-and-complex you will naturally shift to surface mount components:
Once you get past the initial stages of building a working prototype and are progressing to the miniaturization and power optimization standpoint, you’ll want to look carefully at your total energy and real-time current demands, based on your assumptions for reasonable lifetime without battery replacement. Depending on the manufacturer, a CR2032 has a capacity in the 200 to 240mAh range, and can source only around 10mA without the output voltage dropping significantly due to internal resistance.
Point being, you may want to consider something with a little more capacity, or get really fancy and make a wireless charging system (that’s very advanced, and something I would look at only as a second-generation version after everything else has been optimized).
