Step-Triggered Sound Player
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This project creates a step-activated triggered that plays a sound for example when someone steps on your door mat. The sound is stored on an SD card in MP3 format, so it can be any sound you like - like a voice recording or your favorite tune.
Step-Triggered Sound Player Schematic
When there is no weight on the force-senstive resistor (FSR), its resistance is high. This makes the voltage to the transistor low so that it is off.
When someone steps on, for example your door mat with the FSR underneath, its resistance becomes low, and the transistor turns on. When the transistor turns on, the IO2 input of the MP3 player is pulled low and it starts to play.
The R1 resistor's value of 1 kΩ is only a starting point. You might need to go a bit up or down, depending on your FSR (and the weight of your door mat).
The capacitor is there to make sure that a long step on the door mat is converted into a short pulse on IO2 (a long pulse on IO2 changes volume instead of starting to play). The resistor (R2) gives the capacitor a way to discharge after a pulse.
Step-Triggered Sound Player Parts List
How to Build the Step-Triggered Sound Player
You can build this on a stripboard as shown below.
Make sure you cut the strips beneath the mp3 module so that the left row of pins isn't connected to the right (except for ground, you want those sides to be connected). And cut the strips next to ID and D+ from the usb breakout board so that those pins aren't connected to the other things on those strips.
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