I'm using Arduino PWM to drive the 3 leds.. I'd prefer to "fix" the color in hardware, and to keep the software as is (255 for the max value for the led brightness).

hello
I bought a LCD with RGB backlight..but when I put the 3 leds at max voltage I don't get a white color, but a blue-ish white, light azur. And of course every other color that uses the 3 led at the same time is slightly different.
the resistors are soldered on the LCD pcb. Which one should I change, and how?

no it's actually a breakout board sold pretty cheap on Sparkfun..
yes it's not a problem soldering SOIC or SOP packages or similar, but those touch sensor chips with multiple inputs actually only came with smaller packages..

yes but it's the only one I've found on a breakout board, since I can't solder those tiny chips.
What do you mean pushing it? a 5x7 matrix is on the example datasheet, but it doesn't explain how to accomplish that.

thanks for the sincerity, I didn't imagine that the CapSense method is so unreliable.
that will bring me to the MPR121 for sure.
I should understand how can I arrange the input in order to make a 5x7 matrix, so I can understand how many of those chips I need.

I've found the MPR121 Capacitive Touch Sensor chip, made by Freescale, to be a better choice for my project.
It has 12 touch inputs and works on I2C.
on the Freescale website I've read that it is possible to made a 5x7 button matrix using only 1 chip. How can this be done?

hello everyone
I'd like to make a small project that requires more than 30 touch input, a sort of touch keyboard. I only need to know if the input is pressed or not, I don't need a variable value.
Since I'll make the pcb/soldering job on my own, I can only use a PDIP Atmega chip, like the one on Arduino UNO R3, but since I need lot of inputs, I will use something like 2 or 3 of those chips on the same pcb. That would cost less than every other dedicated "touch sensing" ic.
Of course I will use ICSP for every chip to program them.
My questions are:
1) is CapSense reliable enough for such application?
2) If I use the internal oscillator for those AVR that should only detect the touch, the CapSense would still work well?
3) if I don't use an external oscillator, can I still obtain reliable communication between the AVRs using the serial connection?
4) alternatives?

thank you
Dimitri

thanks, I've used now 1.0.4 and it uploads just fine

hi everyone
today I noticed that I can't manage to upload a code on my Arduino Mega 2560,
if the code is bigger than 20.000 bytes (or more or less), it takes forever to upload: it does compile fine, than it says "uploading" but it stucks there, without saying nothing. The ON led lights up, TX and RX flashes togheter every 2-3 seconds.
My sketch is "21.408 bytes (of a 258.048 byte maximum)", I tried to cut out some code to get more or less 19.000 bytes, and it uploads fine, even other sketches works fine.
I'm on Windows 7 64..
what could be the problem?

hello
I'm having some difficulties in cycling between a range of value..

Code:

int c = 0;
int length = 4;
c = -1 % length;
lcd.print(c);

If I use this code I get -1 as result..if I use "unsigned" for c, I get 65535.
I'd like to get 3: (https://www.google.it/#output=search&sclient=psy-ab&q=-1+modulo+4&oq=-1+modulo+4&gs_l=hp.3...1052.1052.0.1909.1.1.0.0.0.0.143.143.0j1.1.0...0.0...1c.1.9.psy-ab.fb5tuCXYaj8&pbx=1&bav=on.2,or.r_qf.&bvm=bv.45512109,d.ZWU&fp=eb10b05648b700fa&biw=1440&bih=755)

If I'm not wrong I used to use % to get always a number in the range of the divisor, both when using negative or positive dividend..
what I'm missing?

ok now I set the whole thing like this:

  TCCR2A = 0b01000001;
  TCCR2B = 0b00001100;

so now I'm using Phase correct PWM, toggling OC2A pin when it reaches OCR2A, and changing the frequency by changing the value of OCR2A, that would automatically give me 50% duty cycle, without setting OCR2B, right?

sure:

Code:

void setup() {
  pinMode(9, OUTPUT);   // OCR2B pin

  TCCR2A = 0b01010011;
  TCCR2B = 0b00001100;
  OCR2A = 84;
  OCR2B = OCR2A / 2; 

}

void loop() {
 
}

If i set  "TCCR2A = 0b00100011"
I get the waveform correctly.

If you just want a 50% cycle you could use CTC and toggle the output pin.

Indeed, what I read on the AVR datasheet says (at the end of Fast PWM mode section) that I can achieve a 50% duty cycle waveform in fast PWM mode by setting OC2x to toggle on each compare match, by setting COM2x1:0 = 1.
I did that but I couldn't get anything from the output (OCR2B output).
Also, I don't understand if the prescaler is used in this mode too (if yes, I guess the calculation for the frequency is the same).

I've been studying the Fast Pwm mode on the 3 timers on those days (using OCRxA as TOP and so varying the frequency).
please correct me if I'm wrong, but seems like I can only use even values for OCRxA if I want a 50% duty cycle,
since to get 50% duty cycle it should result OCRxB+1 / OCRxA+1 = 0,5.
is this correct?

I see..
so for now I will try to get a better accurance using timer overflow interrupt (of course doing some math based on the access-exit timer of ISR and every operation I will do there), If I can't get better accurance I will move to Mega2560