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46  Community / Exhibition / Gallery / Re: LEGO car Arduino controlled by tablet wireless on: March 26, 2014, 12:56:51 pm
You have mangled the URL - a "..." sequence in it means somethuing has abbreviated it. Oh well, a bit of searching and intutiuon and I found the article. The correct url is
47  Community / Website and Forum / Disable notification fails for me on: March 25, 2014, 09:07:07 am
So there is this thread I've particpated in. Then the thread goes off subject, or worse, it is a "less than brilliant" person asking the questions, misunderstanding the answers or rambling.

I thus click the NOTIFY button, and the dialog box asks if I want to DISable notification for the subject, which I do. But I still get emails, and it still pops up in my unread replies.

The other way round seems to work - I read an interesting subject and thus turn notifiction on, even without having contributed to the thread.

Is it me, wrong button, or could the feature need a tweak/patch?
48  Using Arduino / Motors, Mechanics, and Power / Re: FInd the appropriate stepper for microstepping on: March 25, 2014, 08:56:00 am
Irrespective of it being a stepper - when it is "holding" there is no change in the coil currents. Any damped oscillation comes from the force-proprtional-to-deviation of the permament magnet and the electromagnets. I am not sure if it obeys the constraint to oscillate. A servo though will "hunt", because it is an active feedback circuit that applies current when it has deviated, and when it is in the middle applies no current. Both are very similar, but I have not heard a stepper oscillate because there is a load when holding. Servos do. Lots.

Steppers - in general - are not fast. For a really fast movement and accurate positional control you need a dc (or brushless) motor and encoder feedback. Positioning then again gets the same problems as the Servo when holding against load.

49  Using Arduino / LEDs and Multiplexing / Re: shift register newbie fade led question on: March 25, 2014, 08:47:04 am
It has nothing to do with your "bad english". Unless it is very very bad, and it isnt. But "Post your code" means that you cut-n-paste your code into the question and then use the [ # ] button so it cones into a nice little code box. "We" do not care how good or bad your description of what you think your code is doing - and it clearly isnt, as you ask why it fails - we  need to see the code.

The same argument goes for the circuit diagram. Instead of a long explantion just draw it with pencil&paper and then scan it (or use you smartphone or other camera). Of course if you have a circuit/layout software to draw it (Fritzing is free), that is nicer, but not essential.

Just because it happens to you does not make it "very common". (Nor, as some people assume, a totaly new and unique problem). But the number of possible faults is to large to list or guess or explain how to sort them out.

So - post your code, post your circuit, tell us what you want to happen, but what happend instead. THEN you get a quick answer.

 smiley-eek At this moment I am guessing the red wire on the potetiometer is loose. smiley-eek-blue Or the "if ( count > 10 )" should be "if ( count <= 10 )". (Sarcasm off) smiley-wink
50  Using Arduino / Motors, Mechanics, and Power / Re: FInd the appropriate stepper for microstepping on: March 24, 2014, 03:08:41 pm
smiley-sweat  (actually I got it right in the first draft, then I suffert a "mindfart", and did the opposite before posting.)  smiley-red

13Khz is dooable in a normal Arduino, if you dont do too much else.
51  Using Arduino / LEDs and Multiplexing / Re: shift register newbie fade led question on: March 24, 2014, 02:58:01 pm
Which program? What circuit? How am I to guess? Ohh --->,148850.0.html

52  Using Arduino / LEDs and Multiplexing / Re: 7 Segment Display with Push Button Increment on: March 24, 2014, 02:54:12 pm
loop() runs very often. Unless you put a delay() in there it runs at many thousands times a second.

You test the button, if it is down you increment. And then you go round the loop again. It runs very fast so as long as you hold the button down it will increment very fast. You tried to "cure" that by inserting a delay(), but found you increment 5times a second (5 time 200ms delay=1second)

When do you test if the button has been released? That is the essence of yourproblem

You logic needs to remember what the button state was last time round the loop. Only when it changes from low to high do you increm,ent. That will therefor be  single count, as long as you remeber to note the new state of the button.

Look/search for "button debounce" because your next problem will be that you get 2 or 5 counts for every push. In a program that is not time critical (and yours is not at the moment) you can just add a delay(5) after a change of the button state, and it will mask the button bounce.
53  Using Arduino / Motors, Mechanics, and Power / Re: FInd the appropriate stepper for microstepping on: March 24, 2014, 08:40:35 am
3200 stp/rev and 245 rpm gives 3200 * 245 * 60 = 47Mhz step pulse rate ... even with full steps  (200*245*60 = 3Mhz) the A4988 can do no faster than 0.5Mhz (minium pulswidth for Step) You need a different stepper motor controller/circuit and a faster processor than the Arduino.

54  Using Arduino / Programming Questions / Re: Doing things at the same time? on: March 24, 2014, 07:17:30 am
Just because the code compiles, does not mean it is free from "simple beginner faults". It is OK to make mistakes.

Just looking at the code fragment:
se = korrekt.second(), DEC;
    if (se = 10) {
Line one does the following. It evaluates "korrekt.second()" meaning it calls the function. The "," in this context (outside a parameter list to a function)  means after you have evaluted what is to the left, ignore it and evalute what is to the right. Use THAT as the result to pass to the "=". So here we evaluate DEC. This is just a number.  Lastly we take that result and place the result in "se".

(The Arduino reference ommits a few of the less common C/C++ syntax and operators to make it easier to learn. The comma operator is one of these)

I can only guess why you put that ", DEC" there - you think that is necessary to a decimal value from the function. The DEC (or HEX, BIN ...) only have meaning as the second argument to the the print() function. All numbers inside all your variables are binary. The concept "decimal" only takes on meaning when printing (or reading from a file/keyboard) the value, that is the visual representation of the number.

The second line contains an assigment operator "=", not a comparison inside the if. The comparison you probably wanted is "==". This is a very common mistakes, happens to big experienced people too, but unfortunatly a major stumbling block  while one is learning. It should be if ( se == 10 ) .

You then use " { } " for the if-body. Good. It is not needed for a single statement, but it is good practice that makes editing of the code easier.

This was a lengthy response, as you said you are learning - the others have already said the same in shorthand (while I was typing this)
55  International / Scandinavia / Re: Hjälp att komma igång med ett projekt on: March 24, 2014, 06:18:01 am
Bra. Tur at där var en i stan.

Sätt gärna slut resultatet på Exhibition sektionen når det är färdigt (nog).
56  International / Scandinavia / Re: Hjälp att komma igång med ett projekt on: March 23, 2014, 10:49:44 am
Roligt projekt. Du har säkert forstånd på at tänke påhur mycket man kan köra på gatan med den slags modifiktationer/bil.

Det här projekt har 2 huved delar: Omvandling af elektroniska signaler til pneumatik/ventil/magnetkobling och programmering af Arduino. (och en massa bil mekanik) Dom två delarna kan löss och arbetas på uafhängigt af varandra. Jag har förtstånd på det sista. Och til den del menar jag att du tager en Arduino et par LED och et par knapper som du kobblar upp. LED viser ventil signalarna och knapparna er alla dom input signalarna. Så kan vi leka lungt med mjukvaran tils den är "felfri". (Man är aldrig 100% säker. Ganska nästan 100%)

Först kontrol är antal signaler och vad är tidskritisk
#Teckningen viser 8 utgångar och 7 ingångar. Arduino har 20 så det är inte et problem
#Alle input är mänsko styrd, dvs ikke snabbere än 20del sekund eller så. Pneumatikken reagrerer väl heller inte mycket snabbere. Så där är inga tidskritisk faktorer.

Omvandlingen på output är "bare" lite transitor/MOSFET forstärkning. Input skal bare skaleres eller bäst använda en optogate. Faktisk är "elektriska miljöet" i en bil ganska elakt mot fin elektronik - högspännings spikes, ustabil spänning osv. Der skal användas lite mere "afkoppling"  (= R C kredsar) på spänning, och all input/output bör vara opto isolerat och elektronikken i en metal låda.

Så projektet låter OK med en helt standard Arduino (UNO). Du skriver något om en LCD. Där finns flere varianter som enten kobblas på med 6 pins eller en af dom seriella möjligheterene (Serial, I2C, OneWire...) Om det är med parallel (6 pin) så måste det var en Arduino MEGA.

Programmet kan var ganska enkelt : En tilstånds maskin (state engine) som ändrar tilstånd efter input och tid. Jag kan skitsa det och visa hur man gör det til en sketch.

Ditt nästa steg bör vara at visa att du kan koppla up en Arduino med en transitor och LED och en knapp och göra/hitta en sketch med Tryk Tänd - Tryk Släck och få det att funka.

(NB: Jag bor i Köpenhamn . lite långt til Norrköping smiley-wink )
57  Using Arduino / Programming Questions / Re: Programming error in my thermostat sketch on: March 23, 2014, 10:06:41 am
THis logic is wrong
  if (derece > maxdereceold)

If the current tempertaure is greater then the greatest recorded so far - remember this new maximum.
If the current temperature is NOT greater than the last greatest ... do nothing. This "else" in your code is the root of your problems.

Note AWOLs comment: By placing the variables inside the loop() function they will have new "random" values on every loop. Place them outside.

And as it only is a fraction of your code, the above suggestion is just a suggestion
58  Using Arduino / Programming Questions / Re: overriding keyboard on: March 23, 2014, 09:59:50 am
You replace the module in your Arduino installation. Its the same trailing path
(You may want to save a copy of the original calling .orig or something)
59  Using Arduino / Programming Questions / Re: Little help here please on: March 22, 2014, 10:00:17 am
Why do you read the button twice? the same button push does both things (toggle LED toggle servo position), right? Because of the long time to move the servo you program gets confused with the two readings (No I have not studied your code in detail, just skimmed it - I haven't counted "}" if they are te right place, This would be easier if you used the ctrl-T function to format the code and when posting use the "-button between the typewriter and speechbubble - the flow and structure are more evident.
60  Using Arduino / Motors, Mechanics, and Power / Re: Firgelli Compact Linear Actuator - Arduino Controlled? on: March 19, 2014, 02:05:51 pm
It is just a simple DC motor. There is nothing new or different about controlling it. As MarkT writes, two simple ways to do it. Google or those keywords with DC motor arduino or search this site. Its been done thousand times. 12V and 3A. Simple. The limit switches presumably go through a diode and prevent you from pushing the rod beyond its limit, but allows you (hence the diodes) to go back the other way. You can not read their state. There is no feedback at all, so you need to add your own sensor/switch if you want to "know" where the rod is in your program.
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