There are serial LCD modules (UART, SPI, i2c) that can make your life easier if you need to connect 2 or more LCD modules to an arduino board.

http://www.nkcelectronics.com/16x2-Serial-LCD-Module-Blue-with-White-backlight_p_347.html

Kits are ready!!!

UNO R3 protoshield KIT

http://store.nkcelectronics.com/Protoshield-KIT-for-Arduino-UNO-R3_p_308.html

MEGA 2560 R3 megashield KIT

http://store.nkcelectronics.com/MEGAshield-KIT-for-Arduino-MEGA-2560-R3_p_309.html

Hi, I designed new Protoshield boards for the Arduino UNO R3 and Arduino MEGA 2560 R3 boards, announced today.  The protoshield PCBs are available for purchase.




http://store.nkcelectronics.com/Protoshield-for-Arduino-UNO-R3-PCB-only_p_303.html
http://store.nkcelectronics.com/MEGAshield-for-Arduino-MEGA-R3-PCB-only_p_304.html

You are right... I was testing the modification.  I will add the datasheet and publish the modification that is needed to the LiquidCrystal library.

Very cool OLED 16x2 character display compatible with the Arduino LiquidCrystal library (8-bit.  To make it work with 4-bit, a small modification is required to the LiquidCrystal library initialization code)

http://www.nkcelectronics.com/OLED-16x2-character-display_p_202.html

Can you also detail what

my freeduino works in some computers and others doesnt

means?  Doesn't it even power up?  You can program it in one computer but not in another?  What does "work" mean to you?

Windows changes port numbers again if you use different USB ports.  But once you have defined a port number, to a specific Arduino board, plugged to a specific USB port, then you can switch Arduino boards and windows keeps the defined port number.

So why don't we fix this ___ instead of documenting it?

As I see it, it would require only one more comparison, which would execute only in the case of 0. And the code should function the same way it does now.

Am I missing something?

PB

Using the code I posted before you don't need one extra comparison.

[--us]

Apparently --us has the same result as us--, but when it is used in a comparison, the -- before us means that C will decrement the value FIRST, before the comparison, while -- after us means that C will decrement the value AFTER the comparison.  If you use it us--; or --us; alone, both give the same result.  You may say why the creators of C placed such ambiguous operations in the language. Well, once you learn it deeply, it is a language that allows you to write a very compact and intelligently optimized code.  20 years ago, there used to be C programming contests, where you could do very very complex things in just one line of code.  Of course the resulting code was write only, and not meant to be read by mere mortals.

I consider wiring implementation of delayMicroseconds() a bug... the programmer should have used

Code:

if (us-- <= 1)
return;

Probably he/she assumed that nobody wants to invoke a delay routine to wait 0 units of time... but it was a wrong assumption after all.

Confirmed, in winavr float == double (source: "WinAVR / gccavr does not support doubles, in other words: double is considered as float" in http://www.avrfreaks.net/wiki/index.php/Documentation:AVR_Float) and also from the maintainer of avr-libc: http://www.avrfreaks.net/index.php?module=PNphpBB2&file=viewtopic&t=50770&highlight=

The wiki article quoted on single-precision vs double-precision is pretty questionable.  There are/were many floating point formats in use that are not IEEE754 based that still had what they called single and double precision.

All real number representation in a computer architecture is based on some arbitrary use of bits to represent the exponent and the base (is that how you say it in English?  My college education was in Spanish), so I think it is possible to have single and double floating point numbers represented using the same 32-bits.  Just for double, dedicate more bits to represent the exponent and that is it.  I hope my memory is not failing this time...

AFAIK you pass a pointer to the array as a parameter to the function and then just edit it normally inside the function.

And this is an example of what Cheater is suggesting:

Code:

void loop()
{
  byte data[2];

  getdat(&data);
}

void getdat(byte *pdata)
{
  pdata[0] = 'a';
  pdata[1] = 'b';
}

Warning: getdat() doesn't know the number of elements in the array data, so it is better to pass it as a second argument while calling getdat().

Or you can define the array as a global variable in setup() and use it everywhere.

C is an extremely powerful language... remember that almost 100% of all Unixes and Linuxes are written with it...

The audio signal from the PC can be "extracted" through the headphone plug and then use different electronic filters (I guess you need one low pass, several band pass and a high pass filters) to separate the frequencies, then use a vu-meter for each frequency range.  The vu-meter can be implemented using LM339N comparator chips or use specialized audio vu-meter chips.  I haven't built one, but this is how I would start if I need to do it one day.  This is a 100% analog solution without Arduino used.  The MAX7221 is to drive a 7-segment LED display, so I am not sure if you can use it to show a vu-meter effect.

Confirmed, in winavr float == double (source: "WinAVR / gccavr does not support doubles, in other words: double is considered as float" in http://www.avrfreaks.net/wiki/index.php/Documentation:AVR_Float) and also from the maintainer of avr-libc: http://www.avrfreaks.net/index.php?module=PNphpBB2&file=viewtopic&t=50770&highlight=

Are you trying to create a fading effect on one LED or digital PIN?  If yes, then you can use PWM (AnalogWrite).