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6196  Forum 2005-2010 (read only) / Bar Sport / Re: Neuroscience on: October 06, 2008, 04:43:52 am
Bah.  Hard to repair, hard to back up, hard to interface to, tough to reprogram, and the support infrastructure is bulky and messy.
On the contrary, self repairing, almost infinite amount of memory (although access seems to get slower over time) and an amazing range of sensors already interfaced. And the support infrastructure (eating, drinking) is a pleasure in itself. And don't forget the activities required for the creation of new systems  smiley
6197  Forum 2005-2010 (read only) / Bar Sport / Re: Atmel "interesting news." on: October 06, 2008, 03:20:46 pm
my experience with Atmel flash in a mass produced item in the early part of this decade leave me with not the best impression of their skills. The end of line test on flash chips consisted of erasing it and checking for all zeros and programming all ones into it. That was it!!!
Needles to say that we had a 25% return rate on that product.

Some one once told me (at a conference in Las Vagas) that Intel employed all the people not smart enough to work for Microsoft and that Atmel employed all the people not smart enough to work for Intel.

And those not smart enough to work for Atmel work for companies that use Atmel flash?

Just joking mike, couldn't resist  smiley-wink
6198  Forum 2005-2010 (read only) / Bar Sport / Re: New Board - Nice! on: September 15, 2008, 01:19:11 pm
We just installed this yesterday and we're trying to do our best to finetune the spam settings.. It's a bit annoying for us but keeps a lot of spammers out

Considering that from now on I'm manually approving any new user to filter out spammers...
Thanks for your efforts, they are much appreciated.
One bit of fine tuning you may want to consider is to reduce or eliminate the delay for modifying an existing post. I would think that only valid users would bother changing text  they already posted.
6199  Forum 2005-2010 (read only) / Bar Sport / Re: Resistor Group Buy on: September 13, 2008, 12:22:16 am
seeing as how nobody sells a large pack of resistors cheap with the variety i want. i am going to do my own.

I have a supplier that can do 100 each of 86 different types of resistors 1/4 watt carbon film  for $28.

That is 86,000 resistors for $28.

I need 10 total people to join, i have 3 so far, I have offered this to the atlanta arduino group

Once i have 7 People Commit to buying, They can send me $28 via paypal. and should recieve their resistors in about 2 weeks.

Sorry US shipping only.

You can email me at

You may want to consider this source

I purchased 2000 metal film resistors for $15.99 shipped. You get 40 of each value from 1 ohm to 10 megohms (50 different values).

You get fewer resistors than your deal but for less outlay you get 1% metal film, and you don't need 9 other  people to make it work.

p.s. 100 off of 86 values is 8,600 resistors

6200  Forum 2005-2010 (read only) / Bar Sport / Re: Cheap Oscilloscope on: August 06, 2008, 02:19:56 am
Sound cards take an audio input. This means the voltage should be less than  ±1 volt on the auxiliary input, but check the specs for your card. A voltage divider is usually used to drop the voltage into that range and a 10k pot works well for me.
6201  Forum 2005-2010 (read only) / Bar Sport / Re: Cheap Oscilloscope on: August 04, 2008, 06:32:06 am
How about a scope based on Arduino:

Although a sound card would give better resolution (16 bits vs 10) and higher sampling rate (44khz vs around 10khz for the arduino),  but for relatively slow waveforms its nice to have a solution that's easy to customize. You would need to use a second board for the scope if the signal you wanted to measure was generated by an arduino, the scope board will be working flat out sampling and sending the data.

6202  Forum 2005-2010 (read only) / Bar Sport / Re: Cheap Oscilloscope on: July 25, 2008, 02:41:15 pm
Hi melka, how about free?

At the relativly slow data rates of an RC decoder, you could use your computer sound card with some freely downloadable software to display the waveform.

Have a search on google for: sound card oscilloscope
6203  Forum 2005-2010 (read only) / Bar Sport / Re: Hello! on: February 12, 2008, 04:11:47 am
Hi eustace, if the thread was a discussion with examples of driving robots then the hardware interfacing would be where I would think it would go. Or if its to proudly show what you have built then a thread in the exhibition area would be appropriate. Either way, please do share  smiley.
6204  Forum 2005-2010 (read only) / Bar Sport / Re: Hello! on: February 09, 2008, 10:17:15 am
Hi Carsten, welcome to the arduino.  You should have no trouble finding servo and mouse code for your arduino robot. But give a shout if you need any help.

p.s. if you find a 'show new posts' capability, let me know where it is. It would be very useful.
6205  Forum 2005-2010 (read only) / Uno Punto Zero / Re: internal pullup resistors & digitalWrite on: March 28, 2010, 04:10:12 am
It kind of mirrors pin 13 with the flashing LED - you can just plug an LED in without worrying about resistors.

Yes you can do that to make things simpler for beginners, but its not good practice.  The current Arduino boards do not have a resistor in series with pin 13 (its only in series with the internal LED) so the typical red LED plugged in directly will exceed the Atmel recommended pin current.

That, and starting off with external pull-downs are the way many people have been introduced to Arduino, but they are not necessarily the best way to learn.
6206  Forum 2005-2010 (read only) / Uno Punto Zero / Re: internal pullup resistors & digitalWrite on: March 27, 2010, 10:34:04 pm
Hi nick,
This was so you don't have to explain things like the switch pulled the digital in LOW, so digitalWrite HIGH to turn the LED on(it was counter-intuitive to a lot of people).

Yes, a lot of things that beginners need to know can be counter intuitive at first, but explaining it as follows is perhaps clearer:

“when the switch is pushed LOW (digitalRead is LOW) the LED is turned on (digitalWrite HIGH)”

As you say, different people have different takes on this, but FWIW, mine is  that the following code (without the external resistor) is easer:

void setup() {
  // initialize the LED pin as an output:
  pinMode(ledPin, OUTPUT);      
  // initialize the pushbutton pin as an input with pull-up resistor enabled:
  pinMode(buttonPin, INPUT_PULLUP);    

void loop(){
  // read the state of the pushbutton value:
  buttonState = digitalRead(buttonPin);

  // check if the pushbutton is pushed Down
  // if it is pushed, the buttonState will be LOW:
  if (buttonState == LOW) {    
    // turn LED on:    
    digitalWrite(ledPin, HIGH);  
  else {
    // turn LED off:
    digitalWrite(ledPin, LOW);
6207  Forum 2005-2010 (read only) / Uno Punto Zero / Re: internal pullup resistors & digitalWrite on: March 27, 2010, 04:57:44 am
Any of the suggestions in this thread would be an improvement but if the two parameter suggestion is semantically clearer then it deserves further consideration

when you very first start and are introducing the idea of digital input and don't want to introduce to many things at once.
Digital input is almost always introduced using buttons. These require pull-ups so the concept does need to be explained from the start, although often an external pull-up resistor is introduced before internal pull-ups. However I think that many non-technical people would find it easier to get something going if the button example used internal pull-ups instead of the external pull-downs:
  pinMode(buttonPin, INPUT_PULLUP );    
rather than having to understand and deal with : “a 10k resistor needs to be attached from pin 2 to ground” (sounds of user fumbling through pack of components trying to find the correct resistor)

Breaking existing code would be a problem but I wonder if there is any code that relied on the pull-ups being enabled when changing from output mode to input mode. Pull-ups change their state if the pin is switched to output mode and the pin state is changed, so code that does not explicitly set pull-up state when switching from output to input  is a potential source of bugs. Is anyone aware of any code that does switch from output to input that requires pull-ups in a particular state but does not set them explicitly. If not, assuming the current method for setting pull-ups was still supported, old code would not break.
6208  Forum 2005-2010 (read only) / Uno Punto Zero / Re: internal pullup resistors & digitalWrite on: March 22, 2010, 09:45:42 pm
In this case, would INPUT mode explicitly disable the pullup?

I also think this is easy to understand:

INPUT             (input mode without pull-up)
INPUT_PULLUP (input mode with pull-up on)
OUTPUT          (output mode)
6209  Forum 2005-2010 (read only) / Uno Punto Zero / Re: internal pullup resistors & digitalWrite on: March 21, 2010, 09:44:15 am
it is  more consistent with previous code
Hi Ray, could you clarify what previous code the three element version is consistent with?

Pins can be defined as output can benefit from a pullups too.
Pull-ups can only be enabled on inputs.  Because of the way internal pull-ups are implemented on the controller chip, an output pin whose value is low cannot have pull-ups enabled.
6210  Forum 2005-2010 (read only) / Uno Punto Zero / Re: internal pullup resistors & digitalWrite on: March 21, 2010, 02:35:45 am
The benefit of pinMode(9,INPUT_PULLUP) is that its more obvious what the code does than  pinMode(9, INPUT, true);
If the user was not familiar with pulls-ups than context sensitive help on  INPUT_PULLUP would get him relevant information.

Or, if you prefer the three argument version, you could define PULLUP as true and use:  pinMode(9, INPUT, PULLUP)
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