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1  Forum 2005-2010 (read only) / Bugs & Suggestions / New avrdude version, with arduino support on: May 13, 2009, 09:58:59 am
Hi all,

I noticed that the last version of avrdude includes the patch made for the arduino.
It would be nice to use this instead of a custom version. The only difference is the programmer id, which is arduino instead of stk500v1.

2  Forum 2005-2010 (read only) / Syntax & Programs / Re: Pasing value by reference/returning n values on: November 19, 2008, 01:46:21 pm
C does not have the concept of "reference" ala c++. Instead you can use a pointer. It's basically the same as a reference (the main differences being pointer arithmetic and initialization).
Here is a code snippet:

#include <stdio.h>

void my_func(int* a, int *b, int *c) {
  int temp = *a;
  *a = *b;
  *b = *c;
  *c = temp;

void main(void) {
  int i = 23;
  int j = 45;
  int k = 56;
  printf("i=%d, j=%d, k=%d\n", i, j, k);
  my_func(&i, &j, &k);
  printf("i=%d, j=%d, k=%d\n", i, j, k);

a pointer to an integer is declare like this:
int * my_pointer;

Two operators for pointer:
* to dereference a pointer (the value of what is pointed by your pointer)
& to get a pointer to a variable

3  Forum 2005-2010 (read only) / Exhibition / Re: NRL Satellite (ARDUINO IN SAPCE!) on: May 12, 2009, 02:44:16 pm
It's probably STS-127 planned for June 13
4  Forum 2005-2010 (read only) / Exhibition / Re: Car Keypad on: May 15, 2009, 10:32:34 am
i make this sugestion to every1 doing a car project. Get another car battery for your project. that way, you dont have to replace your car's so often

[smiley=huh.gif] That doesn't make any sense.
5  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Help - Random function not working on: December 20, 2008, 12:05:04 pm
What do you want an elf file of? mikalhart's sketch?

Yes that would be perfect. Could you give me the version of your avr-libc, avr-gcc and avr-binutils ? with ubuntu/debian:
$ dpkg-query -s avr-libc
$ dpkg-query -s gcc-avr
$ dpkg-query -s binutils-avr

with other distributions, check your package manager.

Wild guess: the arduino-0012 software was written for AMD64. Perhaps there's a snag hat occurs when running it on Intel 64 bit boxen?

I'm running it on AMD64 and I confirm the bug. Anyway, the Arduino IDE is calling avr-gcc in the background. My theory is a bug in the avr-libc on ubuntu 64 bits. I'm compiling the last version to see if it's changing anything.

Chelmi, who loves is new detective job smiley
6  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Help - Random function not working on: December 19, 2008, 07:29:42 pm
what in the world do libc implementations on the host computer have to do with what is uploaded to the Arduino

IMHO, nothing. But I might be wrong smiley
The only way to understand what is going one is to look at the assembly file for the rand routine and see what is different between the one generated on linux 32/win/OSX and linux 64. Now that I'm in holiday I have more time to do it. I have a 64 bits ubuntu here. I did not run the test but expect to get the strange result. I might need to get a "working" elf file. Anybody can send me one?
7  Forum 2005-2010 (read only) / Frequently-Asked Questions / Powering low voltage motors on: December 01, 2008, 11:13:07 am
Hi guys,

I'm going to make my first attempt at building a robot, Arduino based!
What I'm looking at is a fairly small bot with two wheels and a third contact point.
The motor/gear box would be the Tamiya Double gear box:

My concern is driving/powering these low voltage motors
Now, according to the polulu web site the motors take 3 to 6 volts, but according to the spec (
its 1.5-3V. Who should I believe ? Or maybe they are not refering to the same voltage (?!?).

About driving, I've read on Sparkfun that a standard H-bridge (L293DNE, SN754410) can be used. But the specs say that they have a working range of 4.5 to 36 V.
Is it suited for 3V motors ?

Last question, powering the whole thing.
Should I split the power between the arduino and the motors? I have a 9V battery holder from Ladyada's starter kit (amazing kit by the way). I'm considering using it for the arduino alone and add 4 NiMH batteries for the motors (maybe two is enough?). What do you think?

I think that's it for now smiley-wink . Thanks for your help!

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