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One-Buck Ultrasonic Sensor — Parallax Forums

One-Buck Ultrasonic Sensor

ercoerco Posts: 20,256
edited 2015-10-26 17:49 in General Discussion
10/15 Update: 88 cents. That's just crazy. http://www.ebay.com/itm/New-Arduino-Ultrasonic-Module-HC-SR04-Distance-Sensor-Measuring-Transducer-/181849383810

08/14 UPDATE: Renaming the thread One-Buck Ultrasonic Sensor due to Price Drop: http://www.ebay.com/itm/New-Arduino-Ultrasonic-Module-HC-SR04-Distance-Sensor-Measuring-Transducer-HE-/400756229697

End Update


11/26/12 UPDATE: After a year, I finally changed the thread title from Four-Buck to Two-Buck: http://www.ebay.com/itm/New-Arduino-Ultrasonic-Module-HC-SR04-Distance-Sensor-Measuring-Transducer-Hot-/271040857767?pt=LH_DefaultDomain_0&hash=item3f1b4b46a7

END UPDATE


http://www.ebay.com/itm/270810920267

I lied. $3.95 w/free shipping. Prices on these sensors have been plummeting recently and this is a new low.

I received several of these today, which I paid $4.50 for on October 29. They are pictured and described as SRF-04, which I have used before. 4 pin units. Not PING quality, but very nice. Main bad thing is that they take 2 I/O pins. One trigger, one echo. PING uses just one.

What I received today are newer 4-pin SRF-05 units. Never used these before, and the only info I have found in 10 minutes of searching is at
http://www.robot-electronics.co.uk/htm/srf05tech.htm and
http://www.acroname.com/robotics/info/articles/devantech/srf.html
which implies that these can be used with just one pin, like a PING.

The pinouts on mine are labeled differently than either of these. Mine are labeled:
Vcc---Trig---Echo---OUT---GND so these are some variant or knockoff. I hooked one up to a BS2 tonight using 2-pin mode and it worked flawlessly. I'll request info from the seller about the OUT pin, might take a day to get a reply.

With luck, I'll find out that I can tie the OUT pin to ground and get to one pin mode.
Without any reply or luck, I may tie the OUT pin to ground and release the magic smoke.

So right now, I can't say if they function on one pin, or that the seller will continue to ship 05 units instead of 04's, but they are quite a bargain either way. I just ordered some more. I'm a gamblin' man.
srf05.jpg
1024 x 768 - 127K
«1345

Comments

  • ercoerco Posts: 20,256
    edited 2011-11-16 00:54
    Same as these $11 units: http://www.ebay.com/itm/Arduino-Uno-duemilanove-Mega-Mega-ARM-Ultra-Sonic-range-measurement-module-SRF05-/220885768785?pt=LH_DefaultDomain_0&hash=item336dd15a51
  • Martin_HMartin_H Posts: 4,051
    edited 2011-11-16 06:52
    Once eBay figures out you are interested in certain types of merchandise they hawk similar auctions on their home page. So I've been seeing those sensors and wondering if they worked because the price seems ridiculously low. So thanks for the product report.
  • Luis DigitalLuis Digital Posts: 371
    edited 2011-11-16 07:13
    When I visited eBay page appeared this message: "You bought this item" lol

    Was dispatched on day 8, and I'm still waiting. I've never used an ultrasonic sensor, and I want to experiment with security systems, does not seem enough PIR sensor.

    Thank you.
  • RobotWorkshopRobotWorkshop Posts: 2,307
    edited 2011-11-16 08:24
    The open source LEAF project uses the SRF04 sonars modules as the standard means of measuring distance around the robot. The SRF04 seems to have the same signals as those cheap $4 HC-SR04 sonar modules on ebay. The pinout is slightly different but it is easy to account for that. I've heard from one of those users that they provide about the same results as the SRF04 modules in some initial testing. The only downside was that one of the modules was DOA.

    Now if they start shipping a different version like the SRF05 and it doesn't provide the same results then it is going to upset some people that expect the HC-SR04 modules.

    Robert
  • GordonMcCombGordonMcComb Posts: 3,366
    edited 2011-11-16 09:13
    RobotWorkshop wrote: »
    The open source LEAF project uses the SRF04 sonars modules as the standard means of measuring distance around the robot.The only downside was that one of the modules was DOA.

    Just to put a fine point on it:lol:, the eBay sellers are providing Chinese knockoff boards, not the Devantech SRF-04s and SRF-05s shipped from the UK. The Devantech SRF-05s have similar specs as the 04s, but can use 1- or 2-pin trigger and echo.

    Alex's control board for the Leaf allows for all kinds of variations, so even if someone uses (say) a single-transducer like those from Maxbotics it shouldn't really impact things.

    -- Gordon
  • ercoerco Posts: 20,256
    edited 2011-11-16 09:17
    These SRF05's function perfectly as replacements for the SRF-04 from my initial tests. Last night I tried to get it into one-pin mode (per that first link) by connecting the OUT pin to ground through a 1K resistor (better safe than sorry), but that didn't work. Waiting for a reply from two sellers for more info on the mysterious OUT pin. I haven't found any online documentation yet on this particular SRF05 module.
  • GordonMcCombGordonMcComb Posts: 3,366
    edited 2011-11-16 09:29
    A 1k resistor may be a bit high. Assuming "Out" is the Mode pin, it's going to be pulled high through a pull-up. If you could identify the value of that pullup it would help in knowing whether you can drive the pin low through a resistor.

    -- Gordon
  • ercoerco Posts: 20,256
    edited 2011-11-16 09:48
    I'll drop the resistance lower as I gain courage... :)

    I was also thinking that the OUT pin could be a digital output, triggering at some preset distance. I have seen 4-pin lookalike modules from Sure electronics that only had a digital output like that. I need specs and or more time to play.
  • RobotWorkshopRobotWorkshop Posts: 2,307
    edited 2011-11-16 12:10
    GordonMcComb wrote: »
    Just to put a fine point on it:lol:, the eBay sellers are providing Chinese knockoff boards, not the Devantech SRF-04s and SRF-05s shipped from the UK. The Devantech SRF-05s have similar specs as the 04s, but can use 1- or 2-pin trigger and echo.

    Alex's control board for the Leaf allows for all kinds of variations, so even if someone uses (say) a single-transducer like those from Maxbotics it shouldn't really impact things.

    -- Gordon

    Just to clarify things it was one of the cheap $4 knock off versions that was DOA. I haven't heard anything bad about the real SRF04 modules. You get what you pay for. The cheaper ones may work ok but you may get a substitution you weren't expecting and perhaps there may be a dud mixed in.

    Robert
  • GordonMcCombGordonMcComb Posts: 3,366
    edited 2011-11-16 14:02
    Robert, I figured you meant the imported ones (though to us Americans boards from the UK are also "imported"!). For passers-by I just wanted to make note of the fact these are knockoffs, and aren't from Devantech, despite the product names.

    Besides, both Gerry in the UK and Steve (at Acroname, Gerry's US distributor) would replace the DOA in a heartbeat.

    -- Gordon
  • ercoerco Posts: 20,256
    edited 2011-11-16 15:37
    First useful info I've found on that OUT pin, this implies that it is likely what I suspected, a digital output for a proximity warning. There's a dangerous-looking link for the datasheet that tries to download an exe. file. I requested info straight from the seller.

    http://www.ebay.com/itm/Ultrasonic-Wave-Distance-measure-Module-Ranging-Sensor-/190548468478?pt=LH_DefaultDomain_0&hash=item2c5d92e2fe
  • tonyp12tonyp12 Posts: 1,951
    edited 2011-11-16 17:41
    You always have to be carful with free file storage sites.
    The ads are made to look like the real down load link.

    Here is the real file.
    Ultrasonic.zip
    zip
    zip
    Ultrasonic.zip
    77K
  • ercoerco Posts: 20,256
    edited 2011-11-16 17:48
    That readme file implies that the OUT pin goes low any time an object is detected. I'll check that out and report back. Thanks tonyp12!
  • ercoerco Posts: 20,256
    edited 2011-11-16 20:11
    Only one helpful reply from several Chinese sellers of this 5-pin item, and of the mysterious "OUT" pin, they only say "don't connect" ! :)

    http://www.emartee.com/Attachment.php?name=41365.pdf
  • Martin_HMartin_H Posts: 4,051
    edited 2011-11-17 06:45
    I have a project in the planning stages that requires a whole bunch of distance sensors. So I just purchased four of these, I figure that with shipping delays they should arrive right around the time all my in-flight projects complete.
  • ercoerco Posts: 20,256
    edited 2011-11-17 08:54
    Martin_H wrote: »
    I just purchased four of these, I figure that with shipping delays they should arrive right around the time all my in-flight projects complete.

    Dat's my dawg!

    I gotta figure a way to get a dime per sale off all my Ebay recommendations. You tentatively owe me 40 cents. I'm keepin' track, Pal! ;)
  • Luis DigitalLuis Digital Posts: 371
    edited 2011-11-23 19:30
    Hello again :)

    My sensor is HY-SRF05 (pictured say HC-SR04), and tested it with the object of Parallax "ping.spin", with some modifications because the sensor uses two pins.

    Measured with precision, but after 102 inches (2.5908 meters), usually lose the range.

    Is it normal?

    On the eBay page says: Distance range: 2cm-450cm (4.5 meters).

    Thank you.
  • ercoerco Posts: 20,256
    edited 2011-11-24 01:43
    Interesting, I tested one of mine and it maxed out at ~120 inches, so maybe the long-range accuracy of these cheaper sensors is the limiter. When I get a chance to test some other units, I'll report back if I get different results.
  • Luis DigitalLuis Digital Posts: 371
    edited 2011-11-24 05:31
    erco,

    It also depends on the surface, maybe if we use a larger barrier object sensor can see.

    I am using an object 14 inches diagonal, as a barrier.

    Parallax sensor operates in the range that promise?
  • RobotWorkshopRobotWorkshop Posts: 2,307
    edited 2011-11-29 11:07
    I did receive some of these Sonar modules yesterday to test. When I opened the package I was one module short. The seller said they would get another one in the mail to take care of that.

    The quality looks ok on them but there are a couple important differences worth mentioning. First, the spacing of the transducers is wider than the Standard SRF-04 modules. That may cause problems for those that use a bracket or mounting that needs the sensors in the normal location. Second the mounting holes are very tiny. I'm used to the SRF-04 and the Parallax PING that can use a #4 screw for mounting. For the knock off modules that isn't going to work. You'll need a smaller #2 screw, double faced tape, or glue.

    I think for my main projects I will keep on using both the Devantech modules and the Parallax PING sensors. For odd projects these cheap ones will probably work just fine and I'll be able to find a use for them somewhere.

    Robert
  • ercoerco Posts: 20,256
    edited 2011-11-29 11:16
    Noted. I haven't been able to get any function of the extra alarm pin yet, so these SRF05 modules are functionally the same as 04s. Still functions great and quite a good value for the "let's have 16 sensors all around our circular robot chassis" crowd. :)
  • ajwardajward Posts: 1,130
    edited 2011-11-29 16:08
    Just received three today (05's). Gonna try to get them working later, if I can shake off the oogies! :-|

    @RobotWorkshop It =kinda= looks like there might be room to drill out the mounting holes just a bit. I'll try one tomorrow.

    @
  • Martin_HMartin_H Posts: 4,051
    edited 2011-11-29 16:14
    I am jealous as mine haven't come yet. Maybe my Parallax order will come soon.
  • ercoerco Posts: 20,256
    edited 2011-11-29 16:25
    Man, if everyone here ordered some, I gotta get my 2% kickback...

    FAIL.
  • GordonMcCombGordonMcComb Posts: 3,366
    edited 2011-11-29 16:28
    What are the kind of ultrasonic sensors they use in rear bumper parking aids? Those look fairly rugged. They're also (at least the ones I'm behind in the McDonald's drive-thru) single transducer.

    -- Gordon
  • RobotWorkshopRobotWorkshop Posts: 2,307
    edited 2011-11-29 16:38
    erco wrote: »
    Man, if everyone here ordered some, I gotta get my 2% kickback...

    Sorry Erco, I had come across these on my own surfing ebay before reading your post. No 2% on this one.....
  • ercoerco Posts: 20,256
    edited 2011-11-29 16:39
    @Gordon: Hurry, half off now! Just $104 each at http://www.1aauto.com/1A/Electrical/Cadillac/Escalade/1AZMX00002/327437

    Heck, mine are exactly $100 less. Plus free shipping! :)
  • Martin_HMartin_H Posts: 4,051
    edited 2011-12-05 18:44
    My four sensors arrived over the weekend and I finally got the time to test them today. They seem to work fine, but there is that mysterious fifth pin that doesn't seem to do anything.

    Anyway all the parts for my next build have arrived, so it's time to get cracking.
  • FranklinFranklin Posts: 4,747
    edited 2011-12-05 19:51
    http://www.robot-electronics.co.uk/htm/srf05tech.htm
  • photomankcphotomankc Posts: 943
    edited 2011-12-06 10:49
    Got my three in the mail yesterday. Going to be a bit before I ever get around to testing them out.
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