Replies to This Discussion

Permalink Reply by Andre on April 25, 2012 at 2:27pm

I would also like toknow have the same sonar

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Permalink Reply by herve pellarin on April 28, 2012 at 1:40am

lemme know pls if you have any tip

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Permalink Reply by Adilson Oliveira on September 24, 2012 at 5:38am

Hello

I don't think so. Arducopter reads the analog value of the ultrasonic sensor. This one does not have an analog output and the distance is measured by sending a pulse to the pin trig and counting the time it takes to receive the echo on the pin with the same name. This method was implemented on Megapirates NG.

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Permalink Reply by David Cheney on December 28, 2012 at 11:15am

I'm working on a solution for this. The current MaxsonarXL implementation uses a generic analog source reader with a default median filter. The interface returns centimeters, so a simple wrapper around i.e. the New-Ping library might work, but I'm worried about the delay of measurement and how it might effect the control loop. To get around this I'm building a simple integrator circuit to convert the pulse width from the HC-SR04 into a voltage. This requires an extra pin to clear the voltage between readings, but if it works then it will just be another implementation of the AP_RangeFinder interface.

My first design gives a signal between ~.3V and 3.3V out to about four meters https://www.circuitlab.com/circuit/4etd6v/integrator-for-hc-sr04-ul...

though that design is based on components I had on hand, it really should have a (forward bias) diode between the source and the pull down transistor, and the signal would be much cleaner with a FET. And the transistor's base should be the "clear" pin. And adding a timer and a buffer would make the functionality very similar to the maxsonar devices. 

... it's a work in progress ^_^;;

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Permalink Reply by Adilson Oliveira on December 28, 2012 at 12:09pm

IIRC, the analog output of the maxsonar devices are not the most accurate one. Would make more sense to do the other way around and change the arducopter to read the digital output of the sensors. This way, both could be supported easily. MegapiratesNG already does that.

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Permalink Reply by David Cheney on December 28, 2012 at 12:39pm

though it may be less accurate, it is the fastest output to read. It also requires fewer pins. And in this particular case the HC-SR04 doesn't have a digital output, it's just analog in the time domain.

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Permalink Reply by David Cheney on December 28, 2012 at 11:49am

also, this deserves a cross reference here I think:

http://www.multiwii.com/forum/viewtopic.php?f=7&t=1033&star...

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Permalink Reply by Luis Ramos on December 30, 2012 at 3:12pm

So just to see if i guet this right.... i have buy two of this (one as spar parts) to use in my quad with APM2... will it work???!

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Permalink Reply by David Cheney on January 1, 2013 at 2:51pm

short answer: no.

long answer: check back in about a month and I may have a solution for you. or someone may have done it already and I simply haven't been able to find it.

I currently have a testing problem as I broke one of the motor mounts on my quad and jdrones is refusing to ship me a replacement, and I also haven't finished the software. so right now it's vapor, don't depend on it.

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Permalink Reply by Luis Ramos on January 1, 2013 at 3:49pm

Ok i will get back to you, thanks.

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Permalink Reply by Corey McGuire on January 11, 2013 at 7:02pm

I am also interested in this.  I have both types of sonar, but I am trying to encourage my local community to build rovers and I am trying to get the price point down as far as possible.  As I can get the HC-SR04 down to $1.50 in volume, I would like to be able to use this.

I am working with these on another project, so soon I may be able to help.

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