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1231  Using Arduino / Sensors / Re: Which 9/10dof? on: December 12, 2012, 09:08:48 pm
Both of these sensors already have level translators on the board. The little 6-pin chip is the translator.
1232  Using Arduino / Project Guidance / Re: Using optical (laser not LED) mice to measure distance and speed of robot on: December 12, 2012, 08:52:37 pm
A search for "optical flow sensor" will give you the info you're looking for. There seem to be a great deal of sensor chips out on the market so anticipate problems finding examples for your specific chip.

I've seen a few projects where the user linked an optical sensor to a quadcopter for position stability, so yes what you're describing does make sense.
1233  Using Arduino / Project Guidance / Re: TMP36 Graphing to GNUPlot on: December 12, 2012, 08:44:46 pm
All of your connections appear to be correct. I would suggest attaching a multimeter to the TMP36 to make sure it's giving stable readings. Also verify that the analog pin is OK by replacing the TMP36 with a potentiometer.

FWIW RRDTool is a better option for long-term/historical data charting and recording. IMHO.
1234  Using Arduino / Project Guidance / Re: Building a rover. on: December 12, 2012, 08:27:19 pm
I don't see where a CAN bus fits in.

If I were you, I'd get a small computer (Mini ITX / Micro ATX) and link it to an Arduino via USB; there are lots of small options out there that can be powered with 12V. Let the Arduino control the motors, encoders, rotating cameras/etc. and the computer to handle the navigation, camera data stream, and communications. Looking at the cRio you mentioned I can see where you'd want to get away from that ($3K!).
1235  Community / Bar Sport / Re: To Bing or not to Bing on: December 11, 2012, 09:45:20 am
Quote uses an invalid security certificate.

The certificate is only valid for the following names: , * , * 

(Error code: ssl_error_bad_cert_domain)

It's just a problem with Bing's integration with Akamai.

But whose fault is that? Akamai or Microsoft? I'd vote for Akamai smiley-wink
1236  Using Arduino / General Electronics / Re: Adafruit Solenoid Valve on: December 11, 2012, 09:07:47 am
Or am I missing a trick here?

Ohm's law. The solenoid coil has a fixed resistance. I = V / R.
1237  Using Arduino / General Electronics / Re: Panelizing EAGLE files? on: December 07, 2012, 09:46:44 pm
You can edit the .cam file with a text editor. I'd go through an explanation of how to add another layer (section) but it's pretty self-explanatory.
1238  Using Arduino / Motors, Mechanics, and Power / Re: Motor choice and coupling on: December 07, 2012, 10:59:42 am
This dispenser looks like it will work if you turn the handle back and forth and not necessarily in a continuous rotation. Assuming that's true then an RC servo would be perfect for it; the servo could be mounted on the side of the dispenser with a couple pull rods on the top/bottom of the handle.
1239  Using Arduino / LEDs and Multiplexing / Re: Require assistance with LED Hula Hoop wiring, Seeeduino film, info inside... on: December 06, 2012, 03:52:41 am
shiftOut is software SPI. Simpler to use IMHO.

Any pins can be used with shiftOut.
1240  Using Arduino / General Electronics / Re: How to calculate torque rating for motors? on: December 05, 2012, 09:50:10 pm
It will take very little power to drive the robot on a flat surface, so you need to concern yourself with the maximum thrust you will get. This will be either how much mass you can PUSH with your robot or how steep an INCLINE you can climb.

I'd make a minor nitpick here: with a tracked/skidsteer robot there's a lot more friction to deal with when you're turning. Extremely hard to calculate how much power that requires though, especially with surfaces of varying friction.
1241  Using Arduino / General Electronics / Re: How to calculate torque rating for motors? on: December 05, 2012, 01:28:42 am
You may want to re-think having a motor per wheel with tank treads; if the motors aren't perfectly synced and moving at the -exact- same speed, you will throw the tread (and/or cause problems for the motors/gear-train). Instead, use only a single motor per tread (just like tanks and bulldozers do).

The Rover 5 has four wheel motors and no issues there. I'm a little suspicious how that affects overall battery efficiency though with twice as much gear friction.

The Rover 5 weighs 2.5lbs without batteries so probably a good starting point for you, zharvey. Each motor is 18 watts (7.2V * 2.5A) so as long as you can match that wattage at the RPM you need you should get a good 'bot running.
1242  Using Arduino / LEDs and Multiplexing / Re: Require assistance with LED Hula Hoop wiring, Seeeduino film, info inside... on: December 02, 2012, 11:41:12 am
When you connect batteries through the "BAT" plug the maximum power you can draw from them is 150ma (page 5 of the PDF). This will be much too little to power your LED strip. What you'll probably want to do is use one of your three batteries to power the film and the other two, in parallel, to power the LED strip.

To do this you'd connect the two batteries to 5V/GND on the LED strip. Then also add a ground wire between GND on the strip and the film (the strip and LEDs need to agree on a 0V reference).

1243  Using Arduino / LEDs and Multiplexing / Re: Require assistance with LED Hula Hoop wiring, Seeeduino film, info inside... on: December 01, 2012, 11:59:12 am
Sorry, I misunderstood your question. I'm only familiar with using a sleep timer and just assumed you'd be checking the buttons every X seconds to see if it's time to wake up.

You can use pin D2 or D3 for this which is shown in the I2C block on the film.
1244  Community / Bar Sport / Re: Christmas List on: December 01, 2012, 02:04:07 am
I guess the hardest part is becoming a professor in the first place.

It's not that hard, you just have to fail in the real world.

1245  Using Arduino / General Electronics / Re: Constant current power supplies on: December 01, 2012, 01:23:10 am
The ones I have supply a constant 350ma until the load resistance drops enough to cause it to shut down.  On the high side, they max out at a little over 11V and don't go any higher.  Carefully hooking it to the VIN on an arduino (UNO), they seem to work fine.  The problems may come when the combination of arduino and other devices need more than the 350ma and the thing shuts down.

But isn't that an important issue? These LED drivers are sensitive to the load they're driving; too little load and they shut off, too much load and they shut off. Only under fairly specific circumstances would you have a circuit that could keep that constant load.
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