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31  Forum 2005-2010 (read only) / Exhibition / Re: Arduino + Lego NXT on: October 02, 2008, 12:54:36 pm
..Are you aware of any other method?

To do it right, it sounds like you need an accelerometer, too.  David Anderson provides a pretty detailed description of how he did this on his nBot web site

He explains, "The gyroscope and accelerometer are combined with complementary filters to provide an inertial reference sensor. The ADXL202 accelerometer provides accurate static tilt information, when the robot is not accelerating. The gyroscope can be integrated to provide accurate dynamic tilt information, but the integration tends to drift over time. Combining the two sensors provides a robust inertial measurement."

But, there are apparently a number of different ways to make a balancing robot.  I've heard of at least one person who managed to do it using distance sensors to figure out the tilt based on the distance of the sensor to the ground.  

32  Forum 2005-2010 (read only) / Exhibition / Re: Arduino + Lego NXT on: September 28, 2008, 07:37:57 pm
I'll bite. How are you measuring the tilt?  A accelerometer, a gyroscope or both?  Or, are you doing it with distance sensors?

33  Forum 2005-2010 (read only) / News / Re: avr tutorial on: February 21, 2008, 02:55:44 pm
There was some discussion of this issue over on ladyada's forums, in a thread titled Lesson 3 - delay on reading button press.
34  Forum 2005-2010 (read only) / News / Re: avr tutorial on: February 05, 2008, 10:31:25 pm
i took a break to make some cool shields, but will return to the tutorials soon.
Cool shields are an acceptable excuse  smiley  Is it just the motor shield and boarduino 2, or have you been keeping some of your projects secret...?
35  Forum 2005-2010 (read only) / News / Re: Interesting kit's - cheap on: February 01, 2008, 12:30:38 pm
Wow.  The shipping to the US really is pretty steep.  My only choices for a small order were $40 for 2-3 day FedEx, and $17 for 10-14 day EMS.
36  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Open Source Data Logger Project Using the Ardu on: January 26, 2008, 12:17:14 pm
I would even be prepared to start some sort of contest to kick start this project, throw in some prizes to generate some interest.

Anyone feel that this would be worthwhile?

I think a contest with prizes would discourage people from freely sharing their ideas and collaborating to solve problems.  Maybe it's just me, but it seems antithetical to the sprit of the Arduino community.  
37  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Open Source Data Logger Project Using the Ardu on: January 25, 2008, 11:04:26 pm
The tricky bit is storing large amounts of data.
I would have though the tricky part was getting the Arduino to live long enough off a battery to get a reasonable logging period.  Or, did you anticipate that people would be using wall-warts to plug these loggers into a socket?

As for the amount of memory you need, I've been playing arond with a design for a simple temperature logger, and have found that, using a simple compression scheme, I can get one to three days worth of per-minute temperature readings into the on-board 512-byte EEPROM.  My plan is to use cheap 256kbit eeproms (MUCH larger than the onboard eeprom) for the deployed version of this device, and so memory doesn't look like it's going to be an issue.  

My main concern right now is how long the Arduino can run on battery power.  Without some tricks, it sounds like it won't go long (less than half a day).  I imagine this will require putting the board to sleep in between readings; I know the ATmega168 supports a few sleep modes, but I'm not sure yet how to use them.  It seems like the best solution might be just put the board into a full sleep and add an RTC that can send periodic signals to the Arduino to wake it up.  

Have you guys thought about this?
38  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: FTDI USB drivers on mac os x 10.5 ??? on: February 16, 2008, 10:50:04 am
I'm installing the newest verison of the FTDI drivers for os x, have repaired permissions, I've deleted the kext from /System/Library/Extensions.

You probably know this, but if you install a new FTDI driver, or remove one by deleting the kext from /System/Library/Extensions, you should reboot your machine to make sure the changes take effect cleanly.  

If you're comfortable deleting the kext, then I would start from scratch by deleting the FTDI kext, restarting your machine, reinstalling the FTDI driver and restarting again.  

After the drivers are installed, connect the Arduino to your computer with the USB cable - this should cause the driver to be loaded and the usbserial device to be created.  Then, in a terminal window, type
ls /dev/*usb*
to verify that there's a tty.usbserial device.   If there isn't, check your system logs for error messages.  The following command lets you do that conveniently
bzgrep FTDI /var/log/system.log*
If things are working, then, after connecting the Arduino, the bzgrep command should reveal a message like
/var/log/system.log:Feb 16 07:57:17 teresa kernel[0]: FTDIUSBSerialDriver:        0  4036001 start - ok
If there was a problem loading the driver, I'd expect the system log to contain an error message, instead.

If things still don't work, here's a little shell script you can use to gather information that you can post here on the forums. It includes the commands suggested above and also extracts version information from the kext. To use it, copy the text into a file (like, "") and then run it by saying "sh".
# Report information about the FTDI USB serial driver
echo "[Extensions]"
for KEXT in `ls -d /System/Library/Extensions/*FTDI*` ; do
    echo $KEXT
    find "$KEXT" -name InfoPlist.strings -exec cat {} \;

echo "[Devices]"
ls /dev/*usb*

echo "[System logs]"
bzgrep FTDI /var/log/system.log*

FWIW, I've been using Arduino 0100 successfully with a Diecimila and an old G4 Powerbook under MacOSX 10.4 and 10.5 (now 10.5.2), both with the original FTDI drivers that ship with Arduino 0100 and the latest drivers from FTDI's website.
39  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Can my Arduino be a clock? on: January 19, 2008, 10:33:29 am
A small chip and a crystal gives you very accurate time for under a dollar.
Which chip and which vendor do you have in mind?  I've just done a little poking around for RTCs to use with my Arduino, and while none are more than a few bucks, I haven't found any nearly as cheap as you're describing.  Any specific suggestions you could make would be really helpful.  Thanks!
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