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Max The Magnificent
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What you didn't say...
Max The Magnificent   12/19/2013 1:44:31 PM
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Hi Duane -- what you didn't mention was that we first started bouncing the idea of this sensor board around one Friday afternoon -- when I talked to you the next day (Saturday afternoon) you'd already designed the board and sent a panel off to be fabricated -- you completely blew me away with this. Did you say you use Eagle PCB for these projects?

Duane Benson
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Re: What you didn't say...
Duane Benson   12/19/2013 1:54:46 PM
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Max - I did use Eagle. I currently use the free version. It's limited to two layers and approximately 3" x 4" in board space. It's also limited to non-commercial use. It's a great low-cost way to start designing PCBs. If I ever start to sell any of my creations, I'll need to upgrade to a commercial licence.

Max The Magnificent
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Re: What you didn't say...
Max The Magnificent   12/19/2013 3:01:46 PM
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@Duane: If I ever start to sell any of my creations, I'll need to upgrade to a commercial licence.

That means that so long as you are giving your creations away to me for free, you are OK ... I don't see a downside here LOL

Max The Magnificent
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What?
Max The Magnificent   12/19/2013 3:54:43 PM
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@Duane: In your blog, when talking about th efirst image of the SRF08, you say "The small part, between the two, near the top, is a CdS light-controlled resistor."

What is this used/required for?

Duane Benson
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Re: What?
Duane Benson   12/19/2013 5:29:19 PM
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Max - re CdS cell.

It's just for measuring ambient light. One of the I2C calls returns the value. I might end up squeezing one into my board at some point, but until then, that's one feature it will be missing.

As far as adding temperature, pressure and humidity go, I'd like to have sensors for those environmental factors too.

Max The Magnificent
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Re: What?
Max The Magnificent   12/20/2013 11:23:21 AM
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@Duane: It's just for measuring ambient light. One of the I2C calls returns the value.

My knee-jerk reaction was that someone just happened to throw one on because they had it lying around ... after which it became part of the design.

But then I thought that they may have thought of using the sensor to detect someone coming into a room and activating the room's lights -- in which case they could use the ambient light level to decide whether or not to activate the main lights.

Duane Benson
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Re: What?
Duane Benson   12/20/2013 11:49:49 AM
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Max - I'm not sure what the purpose was. The original documentation just says: "The SRF08 can be used as a light sensor." That type of sensor really isn't senstive enough to detect someone coming into a room,

Max The Magnificent
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Re: What?
Max The Magnificent   12/20/2013 11:52:01 AM
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@Duane: That type of sensor really isn't senstive enough to detect someone coming into a room,

I meant using the ultrasonic sensor to detect if someone came into the room, and THEN use the ambient light sensor to decide whether or not to turn the lights on :-)

Duane Benson
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Re: What?
Duane Benson   12/20/2013 1:27:55 PM
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Ah. That makes more sense. It's early. My brain doesn't actually start functioning until about 10:00am out here.

Max The Magnificent
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Re: What?
Max The Magnificent   12/20/2013 1:31:50 PM
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@Duane: It's early. My brain doesn't actually start functioning until about 10:00am out here.

OK, I'll call you back later (LOL)

Max The Magnificent
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Temperature, Humidity, and Pressure
Max The Magnificent   12/19/2013 3:57:45 PM
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@Duane: I've been told that the accuracy of untrasonic distance measurement readings is a function of temperature, humidity, and atmospheric pressure.

This is probably overkill, but since I'm intending on making my robot a veritable cornucopia of sensors, I'm planning on (a) adding these and (b) seeing how the untrasonic readings varies under different conditions.

a) Are you doing this for your robot?

b) Do you have any advice with regard to these sensors?

Robotics Developer
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Re: Temperature, Humidity, and Pressure
Robotics Developer   12/27/2013 5:19:10 PM
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Max, regarding the ultrasonics make sure you test out the environment that you want to run them in.  In robotic competitions we "saw" problems with utrasonics and diamond plate.  It seems that with diamond plate the ranging varied greaty due to weird reflections.  Be save and test out the environment..  also could be a nice article to write up for others to learn from your experiences.

 

I did very much enjoy the pun :bouncing back and forth"!! Keep up the puns..

Max The Magnificent
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Re: Temperature, Humidity, and Pressure
Max The Magnificent   12/28/2013 12:06:12 PM
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@Robitics Developer: Max, regarding the ultrasonics make sure you test out the environment that you want to run them in...

Good point -- also my robot is going to be on its own, but if I were in a robit competition it might be interesting working on "Stealth" technology re ultrasonic and IR sensors on other robots...

Robotics Developer
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Re: Temperature, Humidity, and Pressure
Robotics Developer   12/28/2013 3:33:32 PM
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Max, the other thing I would remind you of is the sequencing of the ultra sonics (say left, back, front, right) to prevent echos from interfering.  This is more of an issue with multiple robots in a common environment but the side effect is to reduce the processing overhead to 1 or 2 sensors at a time.  The other programming feature that would be nice is to increase the polling on the sensors that are closing in on an object to keep from hitting it.  All that said, it would be most helpful if you had touch bumpers all around to protect your furnature.

Max The Magnificent
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Re: Temperature, Humidity, and Pressure
Max The Magnificent   12/29/2013 2:53:49 PM
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@Robotics Developer: ...sequencing of the ultra sonics (say left, back, front, right) to prevent echos from interfering...

Agreed -- in fact we are thinking of givng the sensor boards the ability to automatically keep on performing a "round-robin" ping one after the other and to kep on doing it -- whenever the main processor is ready (or interested) it can simply request of any senso "what was your last reading?"

 

esutton
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Re: Temperature, Humidity, and Pressure
esutton   8/15/2014 8:46:33 AM
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For a wonderful alternative, check out the PING))) Ultrasonic Distance Sensor by Parallax: http://www.parallax.com/product/28015.

 

 

Max The Magnificent
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Re: Temperature, Humidity, and Pressure
Max The Magnificent   8/15/2014 9:53:22 AM
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@esutton: For a wonderful alternative, check out the PING))) Ultrasonic Distance Sensor by Parallax: http://www.parallax.com/product/28015.

Cool beans -- thanks for sharing

Max The Magnificent
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Re: Temperature, Humidity, and Pressure
Max The Magnificent   12/29/2013 2:54:59 PM
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@Robotics Developr: The other programming feature that would be nice is to increase the polling on the sensors that are closing in on an object to keep from hitting it.

That's a good idea -- thanks for sharing.

Robotics Developer
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Re: Temperature, Humidity, and Pressure
Robotics Developer   12/29/2013 8:30:18 PM
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@Max,

"That's a good idea -- thanks for sharing."

You are most welcome!  Any help that I can provide please contact me!  Robotics encompasses a diverse mix of disciplines and as such it provides an endless opportunity to learn and grow.  As a EE by degree the areas of software, vision, mechanical and systems for robot designs keep me occupied learning and exploring new areas, a wonderful thing for an engineer at heart!

Max The Magnificent
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Re: Temperature, Humidity, and Pressure
Max The Magnificent   12/30/2013 12:19:22 PM
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@Robotics Developer: ...the areas of software, vision, mechanical and systems for robot designs keep me occupied learning and exploring new areas, a wonderful thing for an engineer at heart!

I agree -- one of the reasons for having hobby projects is that it's a great way to learn "stuff" -- for example, working on my my Inamorata Prognostication Engine is affording me the opertunity to learn all sorts of things, like how to calculate the dates of Full Moons and Blue Moons :-)

 

Max The Magnificent
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Re: Temperature, Humidity, and Pressure
Max The Magnificent   12/29/2013 2:56:23 PM
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@Robotics Developer: ...it would be most helpful if you had touch bumpers all around to protect your furnature.

I totally agree -- I'm planning on having my robit bristling with sensors of all types, including bump sensors.

Robotics Developer
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Re: Temperature, Humidity, and Pressure
Robotics Developer   12/29/2013 8:32:50 PM
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Max, consider (if you have the bandwidth and processing power) adding a Kinect to the robot.  It has nice sensor features (depth being one of the really nice ones) as well as vision.  Adding that to the platfrom could provide you with years of experimentation and exploration (pun intended).

Max The Magnificent
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Re: Temperature, Humidity, and Pressure
Max The Magnificent   12/30/2013 12:21:47 PM
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@Robotics Developer: It has nice sensor features (depth being one of the really nice ones) as well as vision.

I might have been tempted to this, but I've already got two of the Pixy Machine Vision things with pan-and-tilt bases, so I'm planning on using these to give me depth perception and stuff

 

Robotics Developer
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Re: Temperature, Humidity, and Pressure
Robotics Developer   12/30/2013 12:39:00 PM
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Max, I would love to understand how you are going to implement depth perception with the two Pixy Machines!  That should be a cool programming project, I am wondering what vision libraries were you planning on using?  The attraction to the Kinect is the built in horsepower/processing for the depth reporting.  Sounds like a fun project for sure.

Max The Magnificent
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Re: Temperature, Humidity, and Pressure
Max The Magnificent   12/30/2013 12:40:29 PM
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@Robotics Developer: I would love to understand how you are going to implement depth perception with the two Pixy Machines!

Me too (LOL)

Sanjib.A
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Re: Temperature, Humidity, and Pressure
Sanjib.A   12/29/2013 4:04:27 AM
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@Max & Duane: Thank you for sharing your project ideas. I was looking for a cheap but fairly accurate ultrasound sensor for a different application (water level measurement of the overhead water tank of my house). I am going to check this out. Btw...why did you chose urtrasound over Infrared? What is the min-max distance directed?

Max The Magnificent
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Re: Temperature, Humidity, and Pressure
Max The Magnificent   12/29/2013 2:50:20 PM
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@Sanjib.A: Btw...why did you chose urtrasound over Infrared? What is the min-max distance directed?


No particular reason -- I was planning on using infraed sensors under the robot to detect edges (like if you put it on a table) -- I've never played with ultrasonics before, so I decided to go that way -- as I recall, they are upposed to be accurate from 2cm to about 450 cm.

 

David Ashton
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SR-04 modules
David Ashton   12/20/2013 12:41:07 AM
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Very nice work Duane.   I was curious about the modules and managed to find a data sheet on the SR-04 here.  They do have some electronics on-board - from the photos they look like they might be just the US devices only on the board.

I have a couple of boxes of US TXs and Rxs - just the bare transducers.  I'd thought of making something like this with them but for $3 it's just not worth it....

 

Max The Magnificent
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Re: SR-04 modules
Max The Magnificent   12/20/2013 11:19:30 AM
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@David: I was curious about the modules and managed to find a data sheet on the SR-04 here.  They do have some electronics on-board...

I think the on-board electronics on the '04 are just for pulse-shaping/controlling the out-going "ping" and detecting/registering/noise-filtering the incoming response...

David Ashton
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Re: SR-04 modules
David Ashton   12/20/2013 5:53:28 PM
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@Max..."I think the on-board electronics on the '04 are just for pulse-shaping/controlling the out-going "ping" and detecting/registering/noise-filtering the incoming response..."

 

From the timing diagram in the datasheet, when you give it an initiate pulse the module will send out 8 40KHz pulses from the transmitter.  Immediately on completion of that it starts the Echo pulse - which it would appear carries on until it detects the end of the echo - that's the pulse you time with your MCU.  

The pulse (by my calculations) is 6.4 CM long....yet the unit can measure down to 2 cm.  I guess working off the trailing edges of the pluses lets it do this.  Quite clever.

greatguin
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Can I buy one?
greatguin   6/10/2014 5:47:08 PM
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I would like to add a sonar sensor to my quadcopter. Can I buy one of these boards somewhere?

Max The Magnificent
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Re: Can I buy one?
Max The Magnificent   8/15/2014 9:52:18 AM
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@greatguin: I would like to add a sonar sensor to my quadcopter. Can I buy one of these boards somewhere?

I don't think Duane is selling these -- but I've copied him on your comment -- send me your email (to max@clivemaxfield.com) and I'll forward thsi to Duane also



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