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Thread: MaxSonar EZ1 range sensor with Phidgets 8/8/8 Interface Kit

  1. Re: MaxSonar EZ1 range sensor with Phidgets 8/8/8 Interface Kit

    Matt or Dave,

    How did you fasten the EZ1 to the perf board as shown in http://forums.trossenrobotics.com/sh...93&postcount=4.

    Thanks,
    Billy

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    Re: MaxSonar EZ1 range sensor with Phidgets 8/8/8 Interface Kit

    If you grind up elf feet they are surprisingly sticky.

    Actually, we didn't do any mounting beyond the soldering. That was enough to hold it in place so we left it alone. You could use double sided foam tape to make it more secure. We have used that on many other sensors in the past.

  3. Re: MaxSonar EZ1 range sensor with Phidgets 8/8/8 Interface Kit

    The ground elf feet kept causing shorts...I'll try the foam tape approach next.

    Thanks for the tip!
    Billy

  4. Re: MaxSonar EZ1 range sensor with Phidgets 8/8/8 Interface Kit

    Eddy, from Wright Hobbies, sent us this schematic for serially triggering an array of EZ1's:



    I like this design because it doesn't require pulse width measurement, like the circuit in the MaxSonar FAQ. Feed it a trigger pulse, and each sensor spews out its range measurement in turn. If you've got an RS232/TTL adaptor, you can send that data straight into your computer. [Edit: Output does not need to be inverted if you are sending it to a PC's serial port, so Q1 is unnecessary in this case. See Eddy Wright's post below.]

    Visit Eddy's site. He's sells some cool stuff and seems like a pretty cool guy.
    Last edited by Dave; 03-06-2007 at 10:46 AM.

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    Re: MaxSonar EZ1 range sensor with Phidgets 8/8/8 Interface Kit

    Eddie does sell a TTL to RS232 converter
    http://www.wrighthobbies.net/catalog...products_id=64

    He says it's a great seller as well. We will probably carry it soon :P

  6. Re: MaxSonar EZ1 range sensor with Phidgets 8/8/8 Interface Kit

    Would Eddie's suggestion work with the 8/8/8? Furthermore, I'm finding that the sensors need from 3-5 range cycles to properly calibrate to give a reliable reading. Does Eddie's approach bypass the need to calibrate?

    Thanks,
    Billy
    Last edited by wmccafferty; 03-02-2007 at 10:52 AM.

  7. Re: MaxSonar EZ1 range sensor with Phidgets 8/8/8 Interface Kit

    Quote Originally Posted by wmccafferty View Post
    Would Eddie's suggestion work with the 8/8/8?
    Nope. You need something that will read RS232 serial data.

    Quote Originally Posted by wmccafferty View Post
    Furthermore, I'm finding that the sensors need from 3-5 range cycles to properly calibrate to give a reliable reading. Does Eddie's approach bypass the need to calibrate?
    I haven't tried it yet, but if I'm reading the data sheet correctly, the sensor only calibrates when it's first powered on. Thus, controlling the sensor via the Rx line, while keeping the sensor powered on, should bypass calibration after the initial cycle.

  8. Re: MaxSonar EZ1 range sensor with Phidgets 8/8/8 Interface Kit

    Thanks for the clarification...both of your responses make sense.

    Billy

  9. Re: MaxSonar EZ1 range sensor with Phidgets 8/8/8 Interface Kit

    Hi Guys,

    I updated the schematic above to include a pull down resistor on Q1's base. This will keep the base from floating when there's no serial data and should ensure a cleaner inversion of the signal through Q1. Q1 is required to invert the serial output so a microcontroller can receive it. Q1 is not needed if you are connecting it to a PC (still need R3 though).

    Ryan Myrda had a good suggestion when stringing together many sonar sensors. You could trigger them in groups of 4 instead of triggering all 16. That would give you more control over which sonars you wanted active. This would require 4 I/O lines from a microcontroller but I think it would be a good approach. All 16 outputs can still be connected together as shown in the schematic.

    Eddy Wright
    Wright Hobbies Robotics
    http://www.wrighthobbies.net

  10. Re: MaxSonar EZ1 range sensor with Phidgets 8/8/8 Interface Kit

    Good call, Eddy. Thanks for the update.

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