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1  Using Arduino / General Electronics / Rail splitter/virtual ground circuit trouble on: April 13, 2013, 02:23:25 pm
I need virtual ground for a 741 op amp. The circuit schematics are here, the later can be simulated:

http://tangentsoft.net/elec/bitmaps/vgrounds/rdiv.png

https://www.circuitlab.com/circuit/y9x79d/rail-splitter/

I have simulated the circuit in three different programs an it always seem to work. However, when I build the circuit on the breadboard, it doesn't work. With 9V DC supply instead of getting 4.5V, 0V and -4.5V I get 9V, 4.5V and 0V. It seems as if the caps weren't even in the circuit. I checked the polarity and the value of the caps and even used different ones. Still don't get any virtual ground, the circuit acts as a voltage divider. A photo of the breadboard circuit:

http://www.flickr.com/photos/alkopop79/8646491414/.

The circuit is damn simple, it puzzles me why it doesn't work. Again, I checked polarities, power, etc. Any help would be appreciated!
2  Using Arduino / LEDs and Multiplexing / Re: Are there any chips that do PWM + Multiplexing like TLC5940 + MAX7219? on: March 03, 2013, 11:13:49 am
I kind of feel bad asking a question. I didn't check the datasheet I admit but I still find it strange why Fungus couldn't answer. Or just not write anything.
3  Using Arduino / LEDs and Multiplexing / Re: Are there any chips that do PWM + Multiplexing like TLC5940 + MAX7219? on: March 03, 2013, 10:52:21 am
I did google it. I still don't understand why is moral authority? Who are you?
4  Using Arduino / LEDs and Multiplexing / Re: Are there any chips that do PWM + Multiplexing like TLC5940 + MAX7219? on: March 03, 2013, 09:40:42 am
It's not the first time I get schooled in this forum. It used to be a haven for those desperate to get help. Nowadays it's just cockiness and schooling. How sad!
5  Using Arduino / LEDs and Multiplexing / Re: Are there any chips that do PWM + Multiplexing like TLC5940 + MAX7219? on: March 03, 2013, 09:35:07 am
No, I went to the Arduino forum to ask a question. I did check loads of tutorials but none of them are about  using multiple ICs. Hence the question, can I daisy chain these ICs?
6  Using Arduino / LEDs and Multiplexing / Re: Are there any chips that do PWM + Multiplexing like TLC5940 + MAX7219? on: March 03, 2013, 04:30:21 am
I wonder if I can daisy chain multiple TLC5940 ICs? I need to drive 25 RGB LEDs.
7  Using Arduino / Project Guidance / Re: Logic analyser on: February 05, 2013, 03:48:53 pm
How about this board:

http://www.digilentinc.com/Products/Catalog.cfm?NavPath=2,892&Cat=18

It's 32 bits, 80MHz clock, 512K Flash and 32K SRAM. Besides the digital pins can endure 5V unlike the Due.
8  Using Arduino / Programming Questions / Re: Control flow troubles on: February 04, 2013, 03:00:13 pm
This time a different code gives me headache. I'm trying to control two DC motors from the serial. The idea is that the direction and the speed of the two motors is determined by commands starting with the character 'l' (left) or 'r' (right). The character is followed then by a numeric value. A function called 'parse' creates a string and then turns is into an int. However the console tells me otherwise... somehow I got lost.

Quote
char inData[10];
int index;
boolean started = false;
boolean ended = false;


void setup()
{
  Serial.begin(9600);
  Serial.println("**************READY****************");
}

void loop()
{
  while(Serial.available() > 0)
  {
    int l=parse('l');
    int r=parse('r');
    drive(5,6,'l','L' );
    drive(9,10,'r','R');
    // Serial.println(Serial.read());
  }

}

int parse(char id){
  char aChar = Serial.read();
  if(aChar == id)
  {
    started = true;
    index = 0;
    inData[index] = '\0';
  }
  else if(aChar == '\n')
  {
    ended = true;
  }
  else if(started)
  {
    inData[index] = aChar;
    index++;
    inData[index] = '\0';

  }

  if(started && ended)
  {
    int inInt = atoi(inData); // Convert the string to an integer
    return inInt;
    // Get ready for the next time
    started = false;
    ended = false;
    index = 0;
    inData[index] = '\0';
  }
}
void drive(int p1,int p2, int dir, char eyed)
{
  if(dir>0){
    analogWrite(p1,dir);
    analogWrite(p2,0);
     Serial.print(eyed);
    Serial.print(" ");;
    Serial.println('f');
  }
  else if(dir<0)
  {
    analogWrite(p1,0);
    analogWrite(p2,dir);
    Serial.print(eyed);
    Serial.print(" ");
    Serial.println('b');
  }
  else if(dir==0)
  {
    analogWrite(p1,0);
    analogWrite(p2,0);
    Serial.print(eyed);
    Serial.print(" ");
    Serial.println('n');
  }
}












Where did I go wrong?
9  Using Arduino / Project Guidance / Re: Logic analyser on: February 04, 2013, 01:05:11 pm
Considering buying it! Thanks!
10  Using Arduino / Project Guidance / Re: Logic analyser on: February 03, 2013, 02:53:33 pm
Hm, that's the thing, my singleboard operates at 5 volts which could fry the Due in no time. What you recommended seems viable, it's not that hard to build voltage dividers (and maybe use resistor arrays to save space). How about using the analog inputs on a Mega? Would the Mega work?
11  Using Arduino / Project Guidance / Re: Logic analyser on: February 03, 2013, 02:45:37 pm
I wonder if the Due can deal with 1MHz logic signals?
12  Using Arduino / Project Guidance / Re: Logic analyser on: February 03, 2013, 12:35:59 pm
I need to see what's happening on the data/address lines. I do need to see the logic state of at least 8 pins.
13  Using Arduino / Interfacing w/ Software on the Computer / Re: SUMP compatible logic analyzer code for Arduino. on: February 03, 2013, 12:17:13 pm
Quote
Then send a 1 or a 2. The program should respond with some status txt. This proves that your program is running!

I've tried this one and indeed, I get data back on the serial monitor. I guess the problem has to do with the settings in OLS. Any ideas?
14  Using Arduino / Interfacing w/ Software on the Computer / Re: SUMP compatible logic analyzer code for Arduino. on: February 03, 2013, 12:09:53 pm
Hi,

I followed the instructions and set up both an Arduino Duemilanove and a Mega. They both appear at Devices and when I click on the Metadata-button, I can see OLS recognises the board. Yet, when I hit Capture begin, I cannot see anything happening. I tried logic signals of different speed and kind and cannot see any waveform on the channels. What am I doing wrong?
15  Using Arduino / Project Guidance / Logic analyser on: February 03, 2013, 12:03:58 pm
Hi,

I've been trying to use Arduino to build a logic scope to debug an 8-bit computer I built. I need at least 8 channels and capture logic signals at 1MHz. I've tried most of the Arduino-based logic scope/oscilloscope sketches and none of them seem to work. So I decided to write a sketch from the scratch (rhyme!). It seems obvious to use a digitalRead function and pass on the readings to the Serial.println. On the recipient side I use Max MSP to visualise the incoming data. Yet I'm not entirely sure if it works. Do I need to set the ADC resolution from 8-bit to a higher value? What is the recommended Baud-rate? Any ideas or experience?
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