Ultrasonic Parking Ranger

Use ultrasonic pings to measure distance to the objects behind and indicate this distance by sending audible tones to your FM car radio.

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The Park Ranger is an ultrasonic-ranging prototype designed to assist drivers who are backing into tight areas. The ranger uses ultrasonic pings to measure distance to the object behind and indicates this distance by sending audible tones to your FM radio. Optional panel-mount LEDs offer visual aid for calibration as well as warning drivers behind you.

Status: Complete

The project features programmable logic, custom ultrasonic ranging circuitry, microcontrollers, and waterproofing techniques.

Project Goal:  The intention of this project is to demonstrate the Amani64’sability to serve as a rapid-prototyping tool for applications typically coveredby proprietary modules. While a commercial ultrasonic-ranging module could be used in this project, the Amani64 is used in instead to tailor the system to our exact needs. The user can drop in blocks of IP, whether open-source or their own, to create a custom application over which they have full control and ownership. A CPLD-based prototyping board is useful for any application that requires logical circuits, whether they be parallel or sequential, that space, cost, and vendor-delivery times are a concern. 

Were this a system I intended to sell, the next step would be to  consolidate the system onto one PCB and into a compact form-factor. The initial prototyping stage, demonstrated in the tutorial, allowed me to evaluate, test and modify the system without being constrained  by third-party modules I do not fully have control or rights to. As I do not intend to sell Park Rangers, I find the prototype sufficient as a permanently deployed system. The construction techniques demonstrated in the following tutorials have sustained the system, deployed in the wet Hawaiian environment and California coast.

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  • Tapping Vehicle Power

    majolsurf02/26/2014 at 01:28 0 comments

    Technical Summary:  In this tutorial you will learn how to power your park ranger by tapping power from the license-plate lighting. The electronics unit will then be powered when the vehicle parking lights are turned on. There are many ways to power your unit, solar, battery, etc; however this is the simplest and cheapest method without long cable runs, complex modifications or additional equipment.

    Parts List:

    (1) Barrel-Power Extension Cable - Digikey CA-2186

    (1) Screwdriver,

    (1) Set Wire Cutters,

    (1) Set Wire Strippers

    (1) Set Wire Crimpers

    (2) 14-16 guage butt-splices

    (1) Digital Multi-Meter

    CAUTION: Always disconnect the car battery before working with the

    electrical systems to prevent injury and vehicle damage. Vehicle

    modifications may void your warranty. If applicable, check with your lien-

    holder prior to making modifications. Proceed at your own risk: Majolsurf

    and the makers of the Amani64 are not responsible for damage caused by

    modifications you make to your vehicle.


  • Project Enclosure

    majolsurf02/26/2014 at 01:25 0 comments

    Technical Summary:In this tutorial we will construct the electronics housing and mount it to the license plate frame. Holes for the stand-off bolts, LED's, transducer leads, and power cable entry point to be drilled. Because the unit will be deployed outdoors, we will need to ensure that the electronics unit is protected from the elements. I will teach you how to create a gasket for your enclosure as well as sealing all entry  points.

    Parts List:

    (1) Project Enclosure (plastic)

    (1) License-Plate Frame (plastic)

    (2) 1/4” Stand-off bolts, washers, nuts.

    (1) Maxbotix-UT Ultrasonic Transducer

    (3) Panel-Mount LEDs, optional, RGY - Digikey 67-1174-ND

    (1) Gasket Material

    (1) Silicon Sealant

    (1) Drill

    (1) 1/4” Drill Bit -Stand-off bolt holes

    (1) 9/16” Wood-Boring Bit - LED holes

    (1) 1/16” Drill Bit - Transducer Leads

    Housing Build:

    Start by marking the drill points on your electronics enclosure, according to your design specifications. For marking enclosures I simply use tailor's chalk. You will need two holes on the bottom portion of the back of the enclosure for the standoffs bolts. You will also need a larger single hole, not shown here, on what will be the bottom of the enclosure to accommodate the power cable. On the face-plate, you will need to make five holes. Three for the panel-mount LEDs, and two for the transducer leads. Start by drilling the enclosure stand-off holes. Next you will need to drill the license plate frame with the same drill bit you used for the stand off bolts, same spacing. Test the fit of the stand off bolts. Run the bolts through the back of the frame. Put one set of nuts onto the bolts some distance away from the frame so that they will serve as a backstop for the enclosure. Slide on the enclosure and secure it with a second set of nuts on the side.

    Lid Drilling:

    Make 3 evenly spaced holes with a 5/8" hole saw for your panel-mount LEDs. Clear out any debris from the holes and check the fit of the LEDs. You may or may not want to snap them into place, depending on the style of the panel-mount LED you have picked for your design. Make 2 small holes spaced accordingly to match the lead spacing of your transducer. Make these holes just large enough for the leads to fit snugly.

    Lid Gasket:

    Next we will make the faceplate gasket to prevent water intrusion into the enclosure. This package of gasket material was purchased at Ace Hardware for about $5. Four types of gasket material are included: fiber, cork, a fiber/synthetic mixture, and rubberized high-density. Either the synthetic or rubberized gasket will work for this application. Trace the outline of both the out edge of the faceplate and the external edge of the flange. Cut out the inside flange fitting with an exacto-knife. Test the fit by placing the face-plate inside. You may also go ahead and cut the external edge either by using the outer line you traced, or by placing the lid on the enclosure and cutting around the outside of the box. Be careful not pull outward on the gasket as you cut or the gasket will stretch or tear and compromise the seal. For aesthetic reasons you may want to trim the excess gasket off, or leave it for additional structural integrity.

    Sealing Entry-Points:

    We will next install the LEDs into the faceplate. Because their connection is an entry-point into the  enclosure, they are a potential water-intrusion risk. We will need to create a seal between the LED and  face-plate by using silicone sealant. 1/3 of the way down from the top of the LED, run a small ring of sealant around it. Seat the LED and wipe away excess sealant from the faceplate. Repeat for the remaining two LEDs. Once the sealant cures, it is not difficult to remove the LEDs should you need to service them, however it does break the seal so you will need to repeat the sealing process when reseated. Next the Ultrasonic Transducer will need...

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  • The Electronics Unit

    majolsurf02/26/2014 at 01:18 0 comments

    Technical Summary:In this tutorial you will learn how to assemble, program,and calibrate the Park Ranger electronics unit. The EU consists of an Amani 64 CPLD shield, an Arduino, an FM transmitter module, one Ultrasonic transducer, and two op-amp modules to amplify return echoes.

    Parts List:

    (1) Amani 64 CPLD Shield -

    (1) Arduino UNO or Duemilinove -

    (1) Maxbotix-UT Ultrasonic Transducer

    (2) Op-Amp Modules - Sparkfun BOB-09816

    (1) FM Transmitter Module - Sparkfun NS73M

    (2) 0.1uF Ceramic Capacitors

    (1) 4.7k Resistor

    (3) Panel-Mount LEDs, optional, RGY - Digikey 67-1174-ND

    (3) 330 ohm resistors, optional, appropriate to your LED drive


    - - Contains Block Symbol, Verilog, and POF files.

    - RADIOping.pde - Accompanying sketch for the Arduino.





  • DIY Park Ranger: Overview

    majolsurf02/26/2014 at 01:15 0 comments

    Introduction Video:​

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