Automatic Cat Scolder

This is a microcontroller project designed to keep cats from doing things they're not supposed to - like eating houseplants (I'm looking at you, Tom!). It does this by making an alarming noise when the cat gets too close.

How it works

This project is designed to run on an Arduino Nano 33 IOT (though it could be configured to run on a different microcontroller with BLE capabilities). The program intermittently searches for a BLE tag worn on the cat's collar and uses its signal strength (the RSSI) to guage the cat's distance from the microcontroller. If the signal is strong enough, it sounds the alarm.

Note: The current alarm sound apparently isn't scary enough to deter my cat, so I'm still working on that part.

Parts and assembly

I used an Arduino Nano 33 IOT and a Grove Piezo Buzzer, though different (but functionally equivalent) parts could potentially be used instead. The following connections need to be made between the microcontroller and the buzzer:

• The buzzer's "GND" pin needs to be connected to a ground pin on the microcontroller.
• The buzzer's "VCC" pin needs to be connected to a digital pin on the microcontroller. This is for powering the buzzer.
• Thu buzzer's "SIG" pin needs to be connected to a digital pin on the microcontroller. This is for sending the square wave signal to the buzzer to produce sounds.

How to run the project

This project is built using the PlatformIO framework. To run the project, you'll first need to install either the PlatformIO CLI or a PlatformIO IDE extension. Once PlatformIO is set up and your microcontroller is plugged in, you can upload and run the project using the CLI run command, or by doing so through your IDE.

Configuration

To configure the project, there are some constants that need to be set:

• TARGET_PERIPHERAL_NAME: The "local name" attribute of the target device (i.e., the BLE tag on the cat's collar).
• LED_PIN: The microcontroller's LED pin number. This is used to turn the LED on and off for debugging purposes.
• BUZZER_POWER_PIN: The microcontroller's pin number that is connected to the buzzer's "VCC" pin.
• BUZZER_SIGNAL_PIN: The microcontroller's pin number that is connected to the buzzer's "SIG" pin.

To set these constants, create a file called constants.h at the root of the project, and then set the constants using the #define directive. Here is an example:

#define TARGET_PERIPHERAL_NAME "CAT-TAG"
#define LED_PIN LED_BUILTIN
#define BUZZER_POWER_PIN 2u
#define BUZZER_SIGNAL_PIN 3u

Debugging

This project uses the microcontroller's LED to give debugging information. It is used in the following situations:

• Each time the target peripheral is detected but is too far away to trigger the alarm, the LED will give two brief flashes in a row.
• If the program restarts (this happens if it can't find the target peripheral 5 times in a row), it will turn the LED on while it's restarting.

In addition, the project writes string-based log messages, which can be read from the microcontroller's serial port using a baud rate of 9600 bits per second.