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eBay Reverse Parking Sensors Teardown

Parking Sensors Kit
Parking Sensors Kit

This is a cheap kit from eBay, to retrofit an older car with ultrasonic parking sensors. 4 sensors are included in the kit, along with a hole saw to fit them to the bumper. There’s a small controller module, and a display module that fits onto the dash of the car.

Controller Module
Controller Module

Here’s the controller module, with it’s row of connectors along the front. The unit gets it’s power from the reversing light circuit, via the red connector.

Main Controller PCB
Main Controller PCB

Removing a couple of screws allows the PCB to be removed. There’s quite a bit on this board, including 4 tunable inductors for the ultrasonic transducers. There’s a linear voltage regulator on the left which supplies power to the electronics, and a completely unmarked microcontroller.

Electronics Closeup
Electronics Closeup

A closer look at the analogue end of the board shows a JRC4558D dual Op-Amp, and an NXP HEF4052B analogue multiplexer. As the microcontroller is unmarked I have no data for that one.

Dash Display
Dash Display

The dash display is housed in another small plastic box, with bargraphs for each side of the car & an overall distance meter.

Display Module
Display Module

Clearly this is a custom module, with the tapered bargraph LEDs on each side & the 7-segment display in the centre. There’s a beeper which works like every factory-fitted unit does, increasing in rate as the distance closes.

Display PCB
Display PCB

The back of the display module has the driver PCB, with yet another unmarked microcontroller, and a TI 74HC164 serial shift register as a display driver. There’s only 3 wires in the loom from the controller, so some sort of 1-wire protocol must be being used, while I²C is the most likely protocol to be talking to the display driver circuit. There’s also a small switch for muting the beeper.

2 thoughts on “eBay Reverse Parking Sensors Teardown

  1. Hi,
    Is there any way to lower the sensitivty of the sensors?
    To make them beep at a smaller distance.

    1. Hi Marko,

      Not that I am aware of, there are no adjustments that I can see.

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