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13381  Forum 2005-2010 (read only) / Bugs & Suggestions / Re: digitalRead not working correctly on: August 28, 2010, 01:35:37 pm
Before a digital input pin can be read reliably it must have either it's internal pull-up enabled, or an external pull up or pull down resistor wired up. If the digital input is wired to an external signal source that can actively sink or source current then no pull-up or down is required. The point is that a digital input pin not wired to anything is not seeing a valid logic level voltage, neither a high or low and should not be attempted to be read.

That make sense?

Lefty
13382  Forum 2005-2010 (read only) / Bugs & Suggestions / Re: Arduino Mega Light Control Board on: August 27, 2010, 10:40:28 am
Determing actual current demand from servos is trick without actual measurement is hard to do. It depends on the specific servo model, mechanical load on the servos, how much travel at any instance and of course if all are moving at the same time or not. It really is a common problem when people try to power more then a single servo from the Arduino's +5vdc source. I'm pretty sure having a external regulated +5 volts with enough current capacity to power the servo will fix your problem.

Lefty
13383  Forum 2005-2010 (read only) / Bugs & Suggestions / Re: Arduino Mega Light Control Board on: August 27, 2010, 10:25:25 am
Quote
the outher day i connected 4 slide pots to the arduino and 4 servos, it worked fine for a minute then all of a sudden the servos went crazy and there pots didnt do anything.

Well first I would ask is how are you powering the four servos? If you are using the +5vdc from the Arduino shield connector then that is probably the cause. Use an external +5vdc at around 3 amps or more to power four servos, or use battey power regulated to +5vdc.
13384  Forum 2005-2010 (read only) / Bugs & Suggestions / Re: IDE/Editor Suggestions on: August 08, 2010, 08:07:14 pm
Quote
Osgeld, it is what many people are used too. How easy would it be for you to change? Every microsoft program supports these keys and it is a small matter for you and a BIG matter for people like me. So why question it?

I tell you what, in the spirit of open source ( ?? smiley-wink ) why don't you post a poll here and see what that forum population thinks?

Lefty
13385  Forum 2005-2010 (read only) / Bugs & Suggestions / Re: Bug with analogReference on: July 29, 2010, 05:39:17 pm
Again the Atmel AVR datasheet is ALWAYS the bible for such issues. The Arduino IDE and board can only do what the chip is designed to do and abide by any restrictions and cautions.

From the AVR datasheet:

Quote
If the user has a fixed voltage source connected to the AREF pin, the user may not use the other
reference voltage options in the application, as they will be shorted to the external voltage. If no
external voltage is applied to the AREF pin, the user may switch between AVCC and 1.1V as reference
selection.

http://www.atmel.com/dyn/resources/prod_documents/doc8161.pdf

From the Arduino reference section ( http://arduino.cc/en/Reference/AnalogReference ) there is a work around for those wishing a work around for the above:

Quote
Warning
If you're using an external reference voltage (applied to the AREF pin), you must set the analog reference to EXTERNAL before calling analogRead(). Otherwise, you will short together the active reference voltage (internally generated) and the AREF pin, possibly damaging the microcontroller on your Arduino board.


Alternatively, you can connect the external reference voltage to the AREF pin through a 5K resistor, allowing you to switch between external and internal reference voltages. Note that the resistor will alter the voltage that gets used as the reference because there is an internal 32K resistor on the AREF pin. The two act as a voltage divider, so, for example, 2.5V applied through the resistor will yield 2.5 * 32 / (32 + 5) = ~2.2V at the AREF pin.



Lefty
13386  Forum 2005-2010 (read only) / Bugs & Suggestions / Re: Bug with analogReference on: July 29, 2010, 01:16:26 pm
Known 'feature' of the AVR chip. From the datasheet in section 23:

"The first ADC conversion result after switching reference voltage source may
be inaccurate, and the user is advised to discard this result."

There is lots of related technical information on the ADC section of the data sheet, so you might want to browse that section.

http://www.atmel.com/dyn/resources/prod_documents/doc8161.pdf

Lefty

13387  Forum 2005-2010 (read only) / Bugs & Suggestions / Re: arduino doesn't connect through usb on: August 02, 2010, 10:23:32 pm
Quote
I just noticed this today and the last sketch I was running was an IR sensor, which was working fine. When I connect it through an external power source it works, but not through usb. Anyone know what could be happening?

Well the USB power goes through a 500ma thermofuse before it powers the rest of the board. Perhaps you have some external component or circuit that is drawing too much current?

Perhaps you can try disconnect everthing wired to the board and load the blink program and see if the on-board pin13 LED works.

Lefty
13388  Forum 2005-2010 (read only) / Bugs & Suggestions / Re: Possible Mega Hardware Problem? on: June 01, 2010, 12:45:15 pm
Just measure the voltage from the power module without being plugged into anything. If it's higher then the max voltage rating of the input caps then that is likely the smoking gun, however a bad batch of caps is also a possiblity.

Lefty

13389  Forum 2005-2010 (read only) / Bugs & Suggestions / Re: new development.... and striking breakthrougs on: April 25, 2010, 08:13:04 pm
I would favor a upgrade to the Xmega series as a more evolutionary step for the Arduino platform. Same basic mega instruction set with additions and lots and lots of bigger better faster peripherals.

I fear a 32 bit Arduino path would cause a forking in the community and less contributions as a whole.

http://atmel.com/products/AVR/xmega.asp?family_id=607

Lefty
13390  Forum 2005-2010 (read only) / Bugs & Suggestions / Re: Add "Seeeduino-style", 0.1" header on: July 16, 2010, 03:28:40 pm
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I've dug through most of the 'Uno Punto Zero' suggestions, and the one I haven't found (which I'd expected) is the proposal of adding a third, 0.1" grid compatible row of headers, like a Seeediuno.

I would be very surprised if the people involved with the 'Uno Punto Zero' effort would ever try and implement any hardware changes at all. I think there are different organizations and/or teams involved with the manufacturing of the Arduino hardware and the team working 'Uno Punto Zero' effort. The latter is to enhance and stabilize the IDE and supporting core libraries only. at least that's my impression of the subject.

Lefty
13391  Forum 2005-2010 (read only) / Bugs & Suggestions / Re: an idea.. on: April 14, 2010, 01:52:37 am
A lot of people needing real time clock/calendar functions either build or buy one based on the DS-1307 I2C RTC chip. Here is a commercial version:

http://www.seeedstudio.com/depot/electronic-brick-real-time-clock-moduleds1307-p-491.html?cPath=48_59&zenid=9f6118c193cee9f8b7337d4df91a2eca

Also pretty easy to build your own on a protoshield board.

Lefty
13392  Forum 2005-2010 (read only) / Bugs & Suggestions / Re: Duemilanove USB connector (suggestion) on: April 11, 2010, 10:46:02 pm
Quote
Has anyone considered using a mini-b connector instead of the full one?

You mean like Seeeduino boards:

http://www.seeedstudio.com/depot/seeeduino-v328-fully-assembledatmega-328-p-439.html?cPath=27&zenid=9f6118c193cee9f8b7337d4df91a2eca

They also provide extra solder pads so all the shield connectors can be on a .1" X .1" grid to facilitate using standard perf board shields.


Lefty
13393  Forum 2005-2010 (read only) / Bugs & Suggestions / Re: 32 bits on: March 16, 2010, 03:16:38 am
Quote
Is it going to be a 32 bit Arduino?
How much would it cost?

At some future date, no doubt. Cost shouldn't be too much more then the current top of the line models.

I would suspect that before a 32 bit AVR is ported to Arduino platform we will most like see a megaX chip board.

Lefty
13394  Forum 2005-2010 (read only) / Bugs & Suggestions / Re: New ideas for forum... on: December 17, 2009, 04:41:06 pm
How about a for sale/items wanted/ for trade section?

Lefty
13395  Forum 2005-2010 (read only) / Bugs & Suggestions / Re: 0017 Serial and port defining on: January 17, 2010, 10:26:27 pm
I've used direct port access and have had no problems doing what I needed to do. However the Arduino reference has this caution:

"Referring to the pin map above, the PortD registers control Arduino digital pins 0 to 7.

You should note, however, that pins 0 & 1 are used for serial communications for programming and debugging the Arduino, so changing these pins should usually be avoided unless needed for serial input or output functions. Be aware that this can interfere with program download or debugging.


DDRD is the direction register for Port D (Arduino digital pins 0-7). The bits in this register control whether the pins in PORTD are configured as inputs or outputs so, for example:


DDRD = B11111110;  // sets Arduino pins 1 to 7 as outputs, pin 0 as input
DDRD = DDRD | B11111100;  // this is safer as it sets pins 2 to 7 as outputs
                        // without changing the value of pins 0 & 1, which are RX & TX "

That from here:  http://www.arduino.cc/en/Reference/PortManipulation


Lefty
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