Ping without microprocessor

UghaUgha Posts: 543
I was wondering... Is it possible to use Ping))) without a microprocessor?

If you used a 555 to generate the start pulse and use an RC circuit on the result... could you get an analog value from the Ping?

(First real post, go me!)

Comments

  • 7 Comments sorted by Date Added Votes
  • FranklinFranklin Posts: 4,747
    edited February 2009 Vote Up0Vote Down
    Since the ping works on the time it takes for a signal to bounce off an object you would need a fairly accurate time base along with some kind of signal detector.

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    - Stephen
  • DufferDuffer Posts: 374
    edited February 2009 Vote Up0Vote Down
    Keep in mind that the Ping sensor, like the Parallax GPS module and the two infrared temp sensors, just to mention a few, is a smart sensor and contains an SX chip as part of their designs. The SX chip handles the recognition of the trigger pulse from the host, the hold-off delay to allow the host to setup to measure the echo pulse width, the generation of the 40KHz echo pulse and finally, the detection of the return echo.
    As a result, the Ping sensor is just about a perfect match for the Basic Stamp's PULSOUT and PULSIN instructions. Most uControllers can meet the requirements of the Ping sensor; a 2-5uS positive trigger pulse, setup to measure pulse width on a pin within 750uS (hold-off) and then accurately measure the pulse width returned by the Ping module.

    Duffer
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited February 2009 Vote Up0Vote Down
    This question actually comes up a lot from college students who call in saying their PING))) does not work. What we found out is that many are trying to trigger the PING))) with a pulse generator and read the response on the scope. When they don’t get a response they figure the PING))) Module is defective. The problem here is that you cannot get a response from a device when you are asserting its line.

    Picture this…you trigger the PING))) with an output pin from some chip (maybe the 555). But when you read the pin with a scope all you see is the trigger pulse. This is because the triggering chip takes the pin from LOW to HIGH and back to LOW, but now it is holding the line LOW. The PING))) cannot makes its pin HIGH to indicate the pulse width.

    When using a microcontroller as soon as the trigger pulse was activated the I/O pin becomes an input allowing the PING))) to assert the line. So to make a truly stand-alone design you have to take this into consideration and make your trigger circuit go Hi-Z after the trigger pulse. I hope this helps. Take care.

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    Parallax Engineering
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  • turkazerturkazer Posts: 1
    edited March 2009 Vote Up0Vote Down
    Hi I change hp 1700 inkjet printer to flatbed to print on the tee shirts everything is ok just I have problem whit sensors and I give errors(paper jump)what kind of microprocessor need I use
    Who can help me?
    Thanks [url=mailto:turkazer@gmai.com]turkazer@gmai.com[/url]
  • Mike GreenMike Green Posts: 22,518
    edited March 2009 Vote Up0Vote Down
    turkazer,
    1) This is called "hijacking", when you ask a completely unrelated question in an established discussion thread. It is considered impolite at best. Do not do it. Post your question in your own thread under the appropriate forum and include an appropriate subject so people can tell what the thread is about.

    2) You question is really about the HP1700 and how it works, not about Parallax sensors. You have to find out how the HP1700 works and what the sensors in it do and that's not a subject for this forum. The name "paper jump" sounds like the HP1700 internal controller is programmed to check for proper paper movement through the mechanism somehow and is not detecting it.
  • kwinnkwinn Posts: 7,590
    edited March 2009 Vote Up0Vote Down
    Ugha, almost anything is possible, the question is if it is worth it. Yes you can build a logic only circuit to use a Ping sensor, but you would be hard pressed to build it for the cost of a small microcontroller, and it would be far less flexible.
    In science there is no authority. There is only experiment.
    Life is unpredictable. Eat dessert first.
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