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1  Using Arduino / Project Guidance / Re: Is it possible to have a stuck relay? on: August 06, 2012, 07:33:58 am
This relay's coil will draw 20mA under 5V when engaged. But it is possible that the in-rush current is higher. So if you are driving the relay directly via an output pin, the pin might not be capable of driving the coil directly. You can test this by measuring the voltage drop across the relay once the pin output goes high.

In any event, you probably should use a simple transistor to drive the relay (also use the catching diode).
2  Topics / Robotics / Re: Balancing robot for dummies on: April 03, 2012, 10:15:07 am
Sounds like you are thinking building a big one smiley. They look pretty powerful for sure, just make sure that your battery source can handle the load. Two of these motors will draw around 2A and the stall current will be much higher.
3  Topics / Robotics / Re: Balancing robot for dummies on: March 29, 2012, 10:32:03 am
For best results, the IMU needs to be placed near the center of the gravity of your build, wherever that is. Typically, the higher the center of gravity is, the easier it is to balance as the timing becomes less critical.
4  Topics / Robotics / Re: Balancing robot for dummies on: March 23, 2012, 07:22:21 pm
I just built a balancing robot using ATmega328 and Arduino libraries myself. I built it using a toy truck as a base, while not as stable as some other builds it is easy on the wallet. Here is a short video:

You can find more information on the theory and the build on my blog (three parts):
5  Using Arduino / General Electronics / Re: Power noise issues with 7805 regulator showing up in analog value on: March 20, 2012, 12:04:01 pm
@veryphatic, I know that you are powering your 7805 using a 12V DC supply. Is that 12V DC supply properly filtered? If you are not using a battery source, chances are that the 1uF cap there is not enough. Try using a 1000uF or higher cap there will dramatically reduce the noise issue.

Also, if you are using a power supply (versus batteries), you will need to consider adequate decoupling, and the trace placement can also affect the noise issue.
6  Using Arduino / Installation & Troubleshooting / Re: Uploading through an USB hub. on: February 24, 2012, 03:44:57 pm

By any chance you know the chipset of your USB hub? Are you running under Linux or Windows? It could well be a compatibility issue of the USB hub.
7  Development / Other Software Development / Re: Arduino 1.0 Makefile on: January 16, 2012, 07:24:26 pm
There was a slight error in my original makefile,
the applet/main.o target needs to be set to depend on main.cpp. Otherwise, compiling after changing main.cpp won't automatically pickup the change (needs a clean first). The makefile needs to be updated as follows:

applet/main.o: main.cpp
test -d applet || mkdir applet
$(CXX) -c $(ALL_CXXFLAGS) main.cpp -o applet/main.o
8  Development / Other Software Development / Arduino 1.0 Makefile on: December 17, 2011, 08:10:29 pm
Hi guys,

I just modified the makefile for Arduino 018 so that it works with Arduino 1.0 now. This means that you can use your favorite IDE to develop Arduino (in my case it is the NetBeans). The latest makefile can be found at my website:

And here is my original post on how to use NetBeans to write Arduino projects.

Since I use Linux, this makefile is only tested under Ubuntu 10.04 (64bit) but it should work on all Linux systems with little or no modifications. For windows users, I think you will have to change things a little bit (for instance I am not sure what the /dev/ttyUSB0 equivalent port would be on Windows).

9  Using Arduino / Installation & Troubleshooting / Re: How the device name (/dev/ttyS0 or /dev/ttyUSB0) is decided exactly? on: December 07, 2011, 03:33:11 pm
Thanks for the link Aeturnalus. I will give it a try.
10  Using Arduino / Installation & Troubleshooting / Re: How the device name (/dev/ttyS0 or /dev/ttyUSB0) is decided exactly? on: December 07, 2011, 11:27:23 am
Thanks awe_cz, it makes sense. I have looked at the udev rule folder under both /etc and /usr but couldn't seem to find anything specific for Arduino though...
11  Using Arduino / Installation & Troubleshooting / How the device name (/dev/ttyS0 or /dev/ttyUSB0) is decided exactly? on: December 05, 2011, 02:38:05 pm
I guess this question has more to do with Linux than Arduino itself. But I am very curious to see how the actual device name is determined. The Arduino on my Linux PC (Ubuntu 10.04) had always showed up as /dev/ttyS0 till a few days ago. I don't remember installed anything unusual, but all of a sudden it changed to /dev/ttyUSB0.

Everything works just fine, but I am just curious as to why. Anyone?
12  Using Arduino / Microcontrollers / Re: Program Loading via Serial Port? on: June 07, 2011, 07:35:55 pm
Mystery resolved. It turned out that since I only hooked up the RX/TX and ground pins to the serial port, I wasn't able to automatically generate the apparently required DTR signal. By pressing the SHIFT key while uploading I was able to see that avrdude was waiting on line:

avrdude: ser_open(): setting dtr

And after seeing this output, I pressed the reset button and bingo everything worked as desired!

         Using Port            : \\.\COM1
         Using Programmer      : stk500v1
         Overriding Baud Rate  : 57600
avrdude: ser_open(): setting dtr
avrdude: Send: 0 [30]   [20]
avrdude: Send: 0 [30]   [20]
avrdude: Send: 0 [30]   [20]

13  Using Arduino / Installation & Troubleshooting / Re: Problem running a flashed code on ATmega8 on: June 07, 2011, 02:10:28 pm
*pLcdLineL = 'C';

Was the pointer properly initialized? Almost seems like there was a memory leak somewhere...
14  Using Arduino / Microcontrollers / Re: Program Loading via Serial Port? on: June 06, 2011, 03:55:28 pm
So, I take it that the bootloader should work with the hardware serial port? Any one has done this before?

The only thing I see that could be a problem is there is no DTR signal in most of the RS232 chips. Whereas in Arduino the DTR is connected to ATMega328's pin 1 (reset) via a capacitor.
15  Using Arduino / Microcontrollers / Program Loading via Serial Port? on: June 06, 2011, 03:26:24 pm
I know that ATmega328 can interface with a physical serial port using a chip like MAX232. I have built such a circuit and have verified that I could send data and receive data via the serial port.

But my question is, does the current version of Arduino bootloader support program loading (e.g. through Arduino IDE) via the physical serial port (e.g. COM1)? The reason I am asking is that when I tried it didn't work and I didn't observe any activity on either the TX or RX line using an oscilloscope. But as I stated earlier, if I use and Serial.write() I could interact via a terminal directly. So I know that the circuit is working properly.
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