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1  Forum 2005-2010 (read only) / Bugs & Suggestions / Getting from Palyground back to other areas on: February 15, 2008, 10:11:56 am
Am I missing something or is it not possible to get back to the main Arduino site from the Playground via a link? I find myself wanting to    go to other areas like the forums. The forums have a link in the header to the home page. I would like to see something similar.

Thanks, Robin
2  Forum 2005-2010 (read only) / Troubleshooting / Re: Diecimila and SN754410 H-Bridge on: February 13, 2008, 09:48:29 pm
Quote
I don't see a ground wire going from the Arduino board to the breadboard

If you go to the original article (http://itp.nyu.edu/physcomp/Labs/DCMotorControl) there are some earlier steps that show the 5V and GND connections from the Arduino. This photo comes from a section discussing the motor connections - so I guess they are left out for clarity. I just followed the article and it worked fine.

Robin
3  Forum 2005-2010 (read only) / Troubleshooting / Re: Getting Arduino Running on PCLINUXOS on: February 02, 2008, 08:11:26 pm
Hello,

I agree, that is a good idea. I was not sure if all members can add to the Playground. I am hoping to get some confirmation that these instructions are clear (and useful) then I will add to the Playground. I have also just got Processing working on PCLOS and that took a little bit of fiddling (The processing GUI would not appear until I removed the java directory shipped with processing).

Thanks, Robin

Quote
If I were you I'd make a new page on the playground and put the instructions there like the Slackware page. smiley
4  Forum 2005-2010 (read only) / Troubleshooting / Getting Arduino Running on PCLINUXOS on: February 02, 2008, 06:42:04 pm
Hello,

I just wanted to let everyone know that I have successfully installed Arduino 0010 on PCLinuxOS 2007. As my Linux installation has been upgraded and several packages have already been installed I cannot say if the following steps will work on a clean PCLOS 2007 install.

I used the Slackware instructions at http://www.arduino.cc/playground/Linux/Slackware as a staring point.

Note that you may have problems if you cut and paste the script steps. I found that the arguments for the configure steps were using a single hyphon or dash when they should be two dashes '--'. That was my 1st issue,

I also found that I needed to install the texinfo package. I installed 4.1.1 from Synaptic and this allowed binutils to build.

I also changed the versions to the latest versions available as of February 1st 2008 and that caused my 3rd problem. Using 2.18 version of binutils caused the gcc-avr build to fail with an error during some assembly related the MOVR not being supported on AVR3. I was able to resolve this problem by using a later snapshot version of the binutils 2,18,50 from ftp://sourceware.org/pub/binutils/snapshots/

This allowed me to build version 4.2.3 of gcc and version 1.4.7 of avr-libc. I was then able to attach the Arduino to a USB Port and it was automatically recognised. All I had to do before starting Arduino was add the /usr/local/avr/bin folder to my path and add the USB port to preferences.txt in my Arduino 0010 folder.

It is possible that the versions used in the Slackware instructions will work fine as long as you fix the dashes for the options and install the texinfo package. Aslo, not that I already had the Java Runtime installed.

I am hoping to use Arduino to teach my sons Electronics and Robotics. I plan on creating a web site to record our experiences.

Thanks, Robin
5  Forum 2005-2010 (read only) / Interfacing / Re: DC Motor Control on: February 12, 2008, 08:44:05 pm
I was able to open the housing and find out some more information about the motors. Inside the rear axle housing there are two RS-380SH motors (http://www.mabuchi-motor.co.jp/cgi-bin/catalog/e_catalog.cgi?CAT_ID=rs_380sh) wired in parallel. Assuming they are the 7.2V nominal versions the current rating looks high (3.2A at peak efficiency) for the SN754410. But I think Eustace's point is important. The motors are probably going to run too fast. Even though there is some gearing in the housing to reduce the rotation. they may well run too fast at the minimum 3V even if I build a better H bridge (the Lego board is using IRL3714 which is a 20V 36A MOSFET). It looks like if I want to use this platform I would need a beefier H-Bridge and perhaps some replacement gearing.

I was hoping to minimize the effort spent on the mechanical platform but this interaction between the mechanical and the electronics is exactly what makes robotics challenging and interesting!

I am really enjoying learning the Arduino by the way!

Thanks, Robin
6  Forum 2005-2010 (read only) / Interfacing / DC Motor Control on: February 12, 2008, 09:44:36 am
Hi, I am working on converting a Lego RC Car (Dirt Crusher RC - Model #8369) to an autonomous robotic car. The plan is to replace the all the electronics with Arduino based motor and sensor controls. I am working on the Motor Control. The car has a Servo to drive the steering and a DC motor to drive the Rear Wheels. The motors and electronics are driven by a 7.2V (1200ma I think) rechargeable battery. I would like to reuse the battery. I have implemented an H-Bridge circuit using Tom Igoe's DC Motor Lab at http://itp.nyu.edu/physcomp/Labs/DCMotorControl using the SN754410. I have tested the circuit without the motor and it is working fine. I am concerned about hooking the motor to the 7.2V battery. I am wondering if this is too much current for the H bridge to handle and also the motor runs to fast any way for my needs so I think I need to reduce current and or speed. It looks like I can control speed using PWM but do I need to reduce the current? If I do need to reduce or limit current how would I enhance the DC motor circuit? Note that eventually the 7.2V battery will be controlling the servo and possibly some of the electronics.

Thanks, Robin
7  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Open Source Data Logger Project Using the Ardu on: February 03, 2008, 11:14:19 am
I have a need for a data acquisition solution and I would be interested to know if it would fit into the scope of this data logger project.

I have a Wood Fired Brick Oven that I built in my back yard. It has several K Type Thermocouples (5 but other ovens could have up to smiley-cool embedded in the mass to measure the temperature of the oven as it heats over several hours. I connected these thermocouples to my PC via a TC-08 Thermocouple Logger from PicoTech (See:http://www.picotech.com/thermocouple.html - I bought the older serial version) and ran a serial cable into the house ( about 50ft). This worked for a while but I the elements got to the logger and it stopped working. The latest version is USB and it's $500 without wireless capabilities. For a replacement I was thinking about a wireless version using Arduino and the XBee shield. To get 8 channels I guess it needs an multiplexer (or is it a demultiplexer?) module, and possibly a thermocouple A/D converter chip, to poll the thermocouples and communicate to the PC.

This real world example seems to highlight some of the common issues with data acquisition/logging applications:
  • Harsh Environments a the point of acquisition
  • Remoteness of the data acquisition point
  • Real Time data is required. In this case it needs to log the data to a real-time display. Logging to a local data store is not an option
  • Data visualization. It needs a software component to graph the results.

Another logging application I have in mind for Arduino is a GPS logger to geotag digital photos. This would involve logging time and location to a data store (SD for example) and then combining that information with   the digital photos based on the timestamp on the photo.

If anyone is interested in a collaborative project for either of these applications. I would be interested. I do not think it needs a competition if there are members of the community that have a common goal. I see advantages for everyone by working on these types of applications under a common data logger/acquisition project. The results could be more modular.

Thanks, Robin
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