Ultrasonic "Radar"

• The Ultrasonic "Radar" (co-designed and co-built by Jason Chung) was our 4th year design project entry. It mimics a standard radar, except instead of using radio waves it uses sound waves to gauge distance. A stepper motor scans the transducer to allow for the creation of a 2D map of the surrounding area.

What does it consist of?

• The Ultrasonic "Radar" consists of 5 major components:
  
  
  1. 16F877 4MHz PIC Microcontroller
  2. Polaroid 6500 Ultrasonic Ranger Module
  3. Motor driver circuitry and unipolar stepper motor
  4. Firmware for the PIC: Programmed in assembly using the MPLAB tool suite.
  5. A GUI, running on Windows that commands the hardware to perform a scan and parses the returned data.
  
  Obviously other support components are required, including a variety of passive components, a MAXIM rs232 level convertor chip, and a hardware mount for the stepper motor and transducer. Please see schematic for components required.
  
  A way to get a programmed PIC is also required. If you have or have access to a programmer a HEX file can be found below.
  If on the other hand you have no access to a programmer a preprogrammed PIC can be purchased from me. Please click here for further details.

What does it do?

• Basically, under command of the GUI the hardware "scans" a 180 degree area in front of it and reports back with distance to objects in range and the headings of the objects.
  The operation is very similar to that of a radar system in an aircraft control center.
  
  On startup the PIC initializes it's hardware and then sits waiting for the GUI to start issuing commands:
  
  
  • The GUI, when instructed, first commands the PIC to prepare for a new scan.
  • It then issues sucessive "get range" commands and "step fwd" commands:
    1. The "get range" causes the PIC to command the ultrasonic module to send a sound pulse; the module returns a signal when it hears an echo.
    2. The PIC times this interval and returns the data to the host system over an RS232 link.
    3. The GUI receives this range and then increments the position of the transducer.
  • After every "get range" command the GUI updates it's screen so that it contains a live display of the information coming back from the hardware.
  • The GUI also contains features such as scan rate adjustments, max distance and "autoscan" which repeatadly scans until commanded to stop.

Enough already! Show me the files...

• Links to the files are as follows:
  
  
  • rangtest.asm - ASM source code
  • rangtest.hex - Compiled HEX file
  • main_electronics_schematic_hi_res.gif - Main electronics schematic
  • regulator_hi_res.gif - Power supply schematic
  • motor_electronics_schematic_hi_res.gif - Motor electronics schematic
  • GUI Source code - Project directory for GUI
  • Design Project Presentation - PDF of the slides from our actual presentation!
  • motor_board_operation.avi - Movie of the motor board operating! (ohh, blinking LEDs...)
  • motor_testing.avi - Movie of the motor turning.

And now, some pretty pictures

• Schematics, please click on image to open full res version:
  Main electronics:
  
  
  Power supply:
  
  
  Motor electronics:
  
  
  Screen capture of GUI in operation
  
  
  Image of preliminary hardware testing
  
  
  Image of first output from the ranger module! :)
  
  
  First output from the PIC! :)
  
  
  Transducer mounted to hardware platform
  
  
  Closeup of stepper motor and main drive gear
  
  
  Closeup of switch that detects "home" :)
  
  
  Polaroid 6500 Ultrasonic Ranger module
  
  
  Main board, still under construction
  
  
  Finished main board!
  
  
  Main board, underside
  
  
  Motor electronics board
  
  
  Motor electronics board, underside
  
  
  Finished mount!
  
  
  Design fair poster
  
  
  

Resources

• Obviously, to do a project like this requires quite a few resources, below are a few I used:
  
  
  • PICLIST - The PICLIST is a email based mailing list consisting of nearly 2000 people. Think of it as a PIC centered think-tank: a group of individuals that have probably seen most of the problems encountered while working with PICs and are eager to help others in solving those problems. I'm a co-admin of the list.
  • Microchip.com - The manufacturer of the PIC Microcontroller line. A great product, a great company. Can't really do anything with a PIC without referencing one of their datasheets or app notes.
  • 6500series.pdf - Datasheet of the Polaroid 6500 Ultrasonic Module
  • acroname.com - Our source for the ultrasonic module. Direct link: 6500 Ulstrasonic Module

Question? Comments?

• If you have any questions about the project or comments feel free to email me at: webmaster@farcite.net