Bin Sentry

Inspiration

We were inspired by our household chores, where we are expected to collect the bins from the end of the road after the bin men have collected the rubbish. An important chore, as if the bin is left too long, it risks getting stolen. We decided that in order to conserve our time and effort, instead of going to the end of the road frequently to check if the bin has been emptied, we would create a device to alert us when it has been collected.

What it does

It is a pair of Arduinos that communicate via 433 MHz radio waves so that when the transmitting Arduino gets moved, the receiving Arduino sets off a buzzer and a flashing LED.

How we built it

We utilised an Arduino Nano, an RX470C-V01 433 MHz transmitter and receiver, a KY020 tilt sensor, a buzzer and an LED. We first constructed the entire system on the Arduino Nano to ensure all hardware worked, resulting in a reliable system that received the signal from the tilt sensor, sent a radio signal at 433 MHz from the transmitter to the receiver over a distance of about 5 centimetres using ASK transmission. Then once this signal is received, setting off the buzzer and LEDs. We then were able to separate it into two devices using an ESP32 that worked remotely. Which produced a functioning solution.

Challenges we ran into

First of all, it took a lot of development and trailing different libraries to get the RF transmitter and receiver to function. Involving the breakage of a couple of transmitters. Second of all, the Arduino Nano did not give out 5V on its 5V pin, so we added an external power source from a battery pack to the VIN pin. Thirdly, out of the pair of Arduino Nanos we had, only one of them was able to compile code successfully. So we constructed a functioning system on one Arduino while we searched for a new one. The search came up with an 8 year old Arduino Leonardo and an ESP32. The Arduino Leonardo did not work but the ESP32 did eventually. Allowing us to finish the product on time.

Accomplishments that we're proud of

We are proud of getting the system working in a local development setting, especially successfully communicating a decimal code over RF 433 MHz signals using ASK. We are also proud of the horrible screeching we were able to produce by pulse modulating the buzzer.

What we learned

We learned to not buy counterfeit Arduino Nanos, and prepare in future for hackathons by having spare Arduinos. We also learned a lot about ASK transmission and RF signals. In addition we learned to use Pico scopes to debug our solutions and discover low voltages.

What's next for Bin Sentry

Develop it to work fully as it could benefit us greatly and seems like a very interesting system to get working fully.

Built With

• arduino
• c++
• nano