Reinventing the Parking Sensor with This Fun Device
Never back into anything again by listening to a parking sensor that plays interesting sounds rather than annoying beeps.
The problem with backup alarms
For anyone that has driven in a city and attempted to parallel park into a tight space or simply navigate a congested parking lot, knowing when the vehicle is about to crash into an obstacle in the rear is quite important. Unfortunately, not all cars are equipped with backup cameras, and for any with aftermarket sensor modules, their incessant beeping can drive someone crazy.
This issue is what inspired YouTuber and maker Guy Dupont to create a new kind of system that taps into the same basic wiring of the already-present sensor but replaces the typical buzzer with a speaker and sound file player instead.
Hacking the sensor
The parking module was originally comprised of a distance sensor, a cheap microcontroller that took readings from it, and a small piezo buzzer that emits a shrieking beeping noise any time it receives power on its two leads. Because the whole thing was already wired into the car's 12V power subsystem, Guy was unwilling to take it apart entirely and start from scratch. Instead, he realized that by measuring the frequency of the beeping/the time between beeps, he could determine the general distance being picked up from the outside sensor.
Required components
In order to interface with the aftermarket parking sensor assembly, Guy built a circuit that featured an optocoupler, which isolates the leads going to the now-removed piezo buzzer from the rest of the circuit. The receiver side of the optocoupler was then attached to a Seeeduino XIAO microcontroller module that reads the pulses on a digital input pin and computes the overall distance (think far, close, and parked).
Loading up custom sounds
The final piece of the electronics was a tiny DFPlayerMini board that houses a microSD card loaded with three sound files — one for each distance. When the Seeeduino XIAO wishes to play a sound, it sends a command over Serial to the module. And best of all, the player's built-in amplifier means that a 4ohm, 3W speaker could be directly connected, thus minimizing the need for extra components.
A case
To clean things up a bit and make the entire system fit into a small area within the vehicle, Dupont designed a wooden case for his backup system using a vector graphics program. Next. he milled the top cover entirely by hand from a piece of MDF, and after some cleanup, inserted the speaker, power jacks/switches, and a bank of connectors for the piezo buzzer leads. The remainder of the case was a simple plastic housing that he had lying around.
Parking the car
For a short test, Guy attempted to back his wife's now-modded car into a space with a couple of boxes that simulated another vehicle. As you can see, and hear, from his video, it worked great. Some of the better sounds included Windows XP effects, clips from the OC television show, and music taken from the Universal Studios globe/spinning text introduction. To read more about this creative project, you can visit his project writeup here on Hackaday.io.