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16  Forum 2005-2010 (read only) / Troubleshooting / serial ports / windows crashes with arduino pluged on: June 07, 2007, 06:05:50 am
since i did not do anything usefull with arduino during the last months i tried to have some fun recently.
but i discovered that arduino gets a very high comport number (com55).
and every single other port (from 1 to 54) is shown to be in use. the most interesting thing is, that only port 1 and 30-40 are shown in the system configurations.
where are the other ports? without seeing them i can't deactivate them. is there any hint how to get a lower portnumber for arduino?

edit: when i try to change any configuration of the comports, the computer crashes with a wonderfull bluescreen.
edit#2: trying a different usb port causes randomly crashes too.

wow. seems like something has messed up my windows. smiley
17  Forum 2005-2010 (read only) / Troubleshooting / Re: What is the best way to connect wires to Ardui on: October 09, 2006, 02:48:36 am
if i understood your question, you are looking for these pin headers:

these headers can be cut into single headers, and you can solder your wire directly on a header. maybe fix it with heat shrink tube.
18  Forum 2005-2010 (read only) / Troubleshooting / burning bootloader in avrstudio on: November 03, 2006, 01:57:10 pm
hello! sorry for posting just another bootloader-question...
since i have a serial isp programmer cable now i want to burn the bootloader to some atmega8.
the "burn bootloader" function in arduino0005 responded with "Programmer is not responding.". but i do not even understand, how this function works (cooperating with every serial isp programmer?).
anyway: i wonder if i can burn the bootloader with the avrstudio software (which works with my isp programmer).
and now the big question
which settings should i use in the avrstudio?

thx! :-)
19  Forum 2005-2010 (read only) / Troubleshooting / midi stepsequencer problems on: September 18, 2006, 05:05:38 am
i built a simple 8 step midi sequencer. i use 2 buttons for navigation and setting the note:
1 button to go to the next step, 1 button to read a potentiometer and set a note number to the actual step.
so i read the buttons very often smiley-wink
during this the sequencer navigates through the steps and outputs the notes.
[dunno how to describe better]

my problem is:
the timing is not "tight". sometimes a note comes out slightly to early.
i tried to get rid of this with 1ms delays after the output of the notes and the button read functions (so that the controller has sort of "time to calculate" smiley-wink ). but that does not solve the problem smiley-sad
and right no, i don't have any idea what to try next. so if anybody could help me...? would be nice smiley
20  Forum 2005-2010 (read only) / Troubleshooting / Re: Voltage regulation issues on Arduino? on: August 23, 2006, 01:28:18 am
usually the 7805 needs at least around 7 or 8 V input voltage. with too low input voltage the output voltage won't reach 5V. i guess what you experiencing ist just too low input voltage.
21  Forum 2005-2010 (read only) / Development / Re: Ideal development kit? on: August 27, 2006, 02:57:29 am
you will probably need a lot of of plug connectors for the connection headers on the board. don't forget to buy an acceptable amount of these smiley-wink
you will also need some 220 ohm resistors (these are very often used, i guess because 5V, which is the mostly used voltage, divided by 220 ohms is something like 20mA, which is the highest amperage which a microcontroller pin can deal with). but also higher resistors will be usefull. 1k, 10k. but if it's not that important: if you run out of higher resistors, you can combine smaller ones. in most cases you won't need resistors with Mega Ohm values.
most LEDs have comparable values, so feel free to get what you like.
some transistors would be fine too. i bought some 2n2222 and some tip120 transistors. i don't think, that i will need more than these during the next weeks.
22  Forum 2005-2010 (read only) / Interfacing / Re: analog in to 4 bit LCD driver on: October 22, 2006, 02:41:41 pm
i gave me a try on an LCD display today. but i failed  :'(
the display just got damn hot and nothing else. guess it's broken now, so i will buy a new one and try again.  :-/
i need the LCD for a present that has to be ready until first days of december, so i am kind of under pressure  smiley-wink
23  Forum 2005-2010 (read only) / Interfacing / Re: arduino as trigger sequencer for modularsynthe on: June 08, 2007, 05:30:04 am
haha sometimes the solution to problems is just as easy as i am stupid:
it was a damn simple pull down resistor for the input...

i'll post pictures of the sequencer as soon as it's ready. can't decide wether to build it into a case of it's own or to put it into my modular systems case as module.
24  Forum 2005-2010 (read only) / Interfacing / Re: arduino as trigger sequencer for modularsynthe on: June 08, 2007, 02:15:35 am
maybe the rising edge of the oscillator signal is not "clear" enough. maybe it takes too much time, so that the interrupt is called many times, when it should be only one time called?
25  Forum 2005-2010 (read only) / Interfacing / arduino as trigger sequencer for modularsynthesizr on: June 07, 2007, 01:40:33 pm
today i had the idea to build a tiny arduinobased trigger sequencer for my modular synthesizer.
the idea is to save the pattern in an array of 8 integers. filled with 1 and 0s.
then i use the interrupt 0 for clocking.
as soon as a rising edge is detected, the actual position of our array is checked to be 1. if it is 1 the output pin should be set to HIGH for a certain amount of time. if the array position contains a 0 nothing happens.

first i tested it with a pushbutton instead of the modular synthesizers square oscillator.
this worked.

but if i use the oscillator as clock, the output changes permanently from high to low when the interrput pin is set high. this should not be happening :-(

details: the oscillator produces a squarewave ranging from -5V to 5V. i used a 1n4004 diode for filtering the negative voltage.
maybe the ~4,3V of the positive square are not enough to give a constant high level? (well, i can't believe this. 2,5V okay - this could be causing problems, but 4,3V is clearly high, for my taste smiley-wink

has someone an idea?

my code is quite simple:

// the LEDpin is used as output for an LED for testing

#define LEDpin 4

int pattern[8] = {1, 1, 0, 0, 1, 0, 0, 0};

volatile int counter;
volatile int state = LOW;

void blink()
  if(pattern[counter] == 0) {    
    state = !state;
  if (counter == 8) {
    counter = 0;
void setup()
  counter = 0;
  pinMode(LEDpin, OUTPUT);
  attachInterrupt(0, blink, CHANGE);

void loop()
  digitalWrite(LEDpin, state);
26  Forum 2005-2010 (read only) / Interfacing / Re: shift registers on: November 08, 2006, 03:49:54 am
i used a 595 shift register for controlling multiple LEDs. worked well, though, you should have no problem using a 595.
27  Forum 2005-2010 (read only) / Interfacing / Re: using "Arduino" fot a stepping motor... on: August 31, 2006, 01:59:49 pm
do unipiolare stepmotors have any advantage compared to bipolar types?
28  Forum 2005-2010 (read only) / Interfacing / Re: How do I know what resistor to use?? on: September 22, 2006, 01:52:16 am

I = V/R = 5V/1kOhm = 5mA      // how do you get 1mA?
you are right. my fault. sorry smiley

29  Forum 2005-2010 (read only) / Interfacing / Re: How do I know what resistor to use?? on: September 21, 2006, 02:11:00 am
the difference between the 1/4W and 1/8W type is the maximum power which the resistor can stand. the electrical power is amperage * voltage. so in the case of a 1k resistor connected between an arduino output and ground:
5V is the output voltage of arduino, so the amperage is 5V/1kohm = 1mA. so the power is 5V*1mA = 5mW (V*I = Power -> V*V/R = Power). the 1/8W would be strong enough to stand this.
30  Forum 2005-2010 (read only) / Interfacing / Re: How do I know what resistor to use?? on: September 06, 2006, 08:11:08 am
Okay, NoObisch Q,

I wonder how I would know how many Ohm a resistor should be, when I am designing a circuit on my own.

Like the KnightRider example, they use 220 Ohm, why (and why use a resistor here anyway??)

I am also using Google offcours, but here I have a feeling I can ask stuff I don't get.
(I have a medical background, doing electronics as a hobby).

Thnx for the time and Greetz from the Netherlands!!

it's basically ohms law. all the time smiley-wink
you need the 220 ohm in this case, because an LED equals a very low resistance as long as it is conductive. and the law of mister ohm says: amperage = voltage / resistance. the voltage on our digitaloutput is 5Volt, the resistance is very little, so we get a huge amperage. our microcontroller digital output is designed to offer ~20mA. it will may get destroyed when an amperage larger than that flows through it. so we use a 220ohm resistance to force an amperage below 20mA.
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