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1  Using Arduino / Sensors / Re: Stabilize analogRead? on: October 12, 2012, 06:42:12 am
Make sure also your power source is stable enough, maybe add some kind of filter (low pass) at the exit of your sensor, and, you can add some kind of "moving average" function to get a stabilized value.
2  Using Arduino / Sensors / Re: Using Ultrasonic Range Finder SRF02 as Motion Detector on: October 12, 2012, 06:37:10 am
@xaral : I'm working on a rather similar solution (motion detection). I've tried both sensors: PIR and US. I've made different tests and finally dropped the US for this use case. It is not the right sensor for your job and let me explain at least one of the reason, which in my case was the main.

The US sensor and the PIR sensor have really distinct detection area. You will end up with having one sensor detecting a motion and the other not, and vice versa. In my particular case, I had to be in a really narrow area to be able to detect a motion with the US sensor whereas the PIR sensor was detecting the motion...

If you want an advice, forget your US sensor for any motion detection solution and focus only on PIR sensor(s). To avoid false positive, keep your two sensors, choose a position where their detection areas cross each other and only trigger an action if BOTH detects a motion.

Good luck.
3  Using Arduino / Sensors / Re: ABS wheel speed sensor - measuring vehicle speed on: October 09, 2012, 10:50:55 am
You should give the hardware way a try first. The less your arduino card do to clean the signal, the more features you can to your program...

I've previously thought about a similar feature (being able to measure the speed based on a hall effect sensor). One of my lead was using a frequency to tension converter. Thus, no need to deal with interrupts, just have to read an analog pin.
4  Using Arduino / Sensors / Re: How to use 2 IR receivers ? on: October 09, 2012, 10:30:05 am
Where I work we had a Satellite box at one end of the building and someone who wanted to channel change it one floor down and at opposite side of building. We de-soldered the IR LED from the remote and placed it on about 50 meters of screened audio cable at the satellite box and it worked a charm. I would assume IR receiver would work just as well.

That's even better. Thanks for sharing. If my logical gate does the trick, I'll solve my problem!
5  Using Arduino / Sensors / Re: How to use 2 IR receivers ? on: October 09, 2012, 02:42:07 am
Just to contribute to the knowledge base: I've tested with some 5 meters long cables, clearly not the best quality cables, and my (single for the moment) receiver works like a charm.
=> That's a good point!

I've have to try with a second receiver and a logical gate now (have to buy both before).
6  Using Arduino / Sensors / Re: How to use 2 IR receivers ? on: October 05, 2012, 09:04:45 am
So an AND gate is what I need to test the low cost version, right ?

If so, should I choose a TTL or CMOS gate ? Any model in particular (I've found this one for instance: CD4081 ( ?
Do I need something else ? like some kind of (frequency) filter to remove noise from my signal?

Is a shielded cable worth the price in my case ?
7  Using Arduino / Sensors / Re: How to use 2 IR receivers ? on: October 05, 2012, 05:32:41 am
Hi, thanks for your answers.

First, here is the link mentioning the AND gate to couple two receiver :,20794.msg153653.html#msg153653

The AND logic seems odd to me too, the OR is more what I'm looking for.
In fact, I don't need to know which receiver receives the signal, both will act exactly the same in my program. I just need two of them because of the distance between the two points.

My need could be satisfied with the OR gate solution. Could you please tell me more about this ? Should I choose a CMOS gate ? a particular model ? do I need something else to wire the whole thing ?

@Chagrin : do you need it won't work due to the cable length ? Should I try with a shielded cable ? What is the maximum cable length you think I can use ?

NOTE: I may be able to reduce the cable length this way:
each 10 meters cable may become 4 to 5 meters.

Is a RS485 based solution more robust ?

Thanks for your tips
8  Using Arduino / Sensors / How to use 2 IR receivers ? on: October 04, 2012, 07:23:42 am
Hi all,

I need to be able to read some IR signals at two different physical points too far from each other to use the same receiver. See my ASCII drawing :

  0                                                                                                                 0
-+-                                                                                                              -+-
  |    <-3m->   IR recv1<-10m cable->[Arduino]<-10m cable->IR recv2   <-3m->         |
 /\    <------------------------------  ~26 meters  ------------------------------>  /\

As you can see, because of the distance between the two points, a single receiver can't work.
That's why I need a second receiver.
They won't receive a signal a the same time

How can I get this to work ?

NOTE : Ken Shirriff (IRRemote library) talked many months ago about "AND-ing" the output. It wasn't clear to me...

Thanks for your help.
9  Using Arduino / Microcontrollers / Re: The Armalite, SAM3 32-bit "Arduino-Due-compatible" design on: March 19, 2012, 09:41:52 am
Since Due doesn't seem to arrive soon, your board is an interesting alternative.
Good job, far away from what I can modestly understand.
10  Using Arduino / Project Guidance / Re: Reliable Bluetooth with Aduino Uno ? on: December 19, 2011, 04:14:41 am
One more question, since I'm about to receive a low cost BT shield among many other things :

How to determine the right baud value ? I want an optimized set up and I don't want to waste some resource. The baud rate can vary a lot, I just want to pick the right value for my use case.

11  Development / Other Software Development / Typo in documentation on: December 17, 2011, 11:10:32 am
Just to mention a typo in the doc : page "", look for "Four contstants are predefined", where "contstants" should be "constants"
12  Using Arduino / Project Guidance / Re: Reliable Bluetooth with Aduino Uno ? on: December 11, 2011, 03:36:37 pm
@Si : thank you for you answer. Glad to hear everything's gonna be alright with this kind of module. Blue smirf is quite expensive, that's why I'm not considering it.
I can't use a wired connection, because the piece of software I'd like to communicate with is a closed source (but free) software, waiting for a ... bluetooth connection smiley

@Techone : We will be at lea two of us developping something around this shield. I won't develop (at least at the beginning) something on my phone as the software I want to use already exists (and works perfectly). For your problem on the phone side, did you read the Sun official documentation about J2ME and bluetooth support ( ? It doesn't seem to be too complicated (but my point of view is a little biasied as I'm a Java developer).
13  Using Arduino / Project Guidance / Re: Reliable Bluetooth with Aduino Uno ? on: December 10, 2011, 02:22:12 pm
Does anyone use bluetooth shield ? I'm surprised not to have a single answer.

Any help/comment appreciated. I'm gonna choose a module like Itead BT Shield 2.2 if no answer.
14  International / Français / Re: Arduino et les shields : demystification svp on: December 10, 2011, 07:47:51 am
Bon, je pense que je vais donc me lancer rapidement (je prépare mes commandes) : hâte de développer mes premiers sketches et voir des choses bouger/clignotter smiley Ca va me changer des développements purement applicatifs où l'interaction ne passe que par une IHM web !

Merci pour ces réponses constructives !
15  International / Français / Re: Arduino et les shields : demystification svp on: December 08, 2011, 05:08:07 pm
Merci skywodd : tes reponses sont claires, précises et efficaces.

J'ai lu l'annonce de la (prochaine) nouvelle carte entrée de gamme (leonardo). Est-ce interessant d'attendre quelques semaines (vu qu'elle semble finalisée) et la prendre plutôt qu'une Uno?
A priori, elles sont quasi identiques (sauf le support de l'USB, natif dans le hardware de la leonardo), donc j'imagine que la compatibilité avec les shields sera donc à 100% ?
Le µP est il plus performant aussi ou bien identique sur ce point ?

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