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#3580229 - 05/26/12 11:53 AM Hall sensor setup BU0836  
Joined: Jul 2011
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Volans Offline
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Hi. I'm in the process of building two "unijoint type" DIY flight sticks ( http://www.d13-th.ro/forum/index.php/topic,6324.0.html )
Therefore, I run into trouble... smile : I'm using Leo Bodnar BU0836 card, cubic neodim magnets and hall sensors from his site (the Allegro A1302 ).
Axis are working well, BUT instead of 1024 steps (10 bit) I got only 280 steps on X axis and 208 on Y axis no matter what: changed the magnet from small ones to some really big (and wider) ones, changed the sensor to the edge of the magnet (supposed to increase the accuracy), swapped various Allegro A1302 sensors, then I replaced them with some hall sensors found in an Saitek X52, swapped the BU0836 with another one, STILL ALWAYS got the dreaded "280" on X and "208" on Y.... Funny thing is that when I swap the two sensors (X to become Y and viceversa), the same sensor that read 280 steps on X now read 208 steps on Y.
Then I tested with A BU0836A (12 bit) card and got 524 steps on X and 789 steps on Y. Tried all the above result: same hardcoded values
Then I tested with a BU0836X (12 bit) card and got 1057 on X and 1092 on Y Again, rock stable values no matter what. Only when I used the tiniest magnet available values start to decrease.
(How I did my experiments:I leaved one 10mm cubic neodim magnet in place,then and removed the other one, replacing him with various magnets, replacing the sensors, cards..etc. The only common element is that 10mm magnet left)

BU0836 "vanilla"


BU0836A


BU0836X


Now I'm really running out of ideas so I adress to you good people my deepest and sincere "PLEASE HEEEEELP...." biggrin

PS : Maybe I'm using somehow too strong magnets, and the magnetic field interfering?

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#3580465 - 05/26/12 07:53 PM Re: Hall sensor setup BU0836 [Re: Volans]  
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Bluedeath Offline
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It works fine for me with 5 mm magnets on the sides if the sensor! What distance O you have between magnets and the sensor?

Last edited by Bluedeath; 05/26/12 07:54 PM.

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#3580473 - 05/26/12 08:05 PM Re: Hall sensor setup BU0836 [Re: Volans]  
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Volans Offline
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Well, some update: every BU card have 8 axes. I tried all the axes and every one, apart from X and Y, will report 1024 steps (and 4096 for Bu0836A and X) as soon any magnetic field is applied to hall sensors.... Apart X and Y....
I have two BU0836 (10bit) cards, one BU0836A (12bit) and two BU0836X (12bit), every single card behaving just as described above: poor (reported) sensitivity on X and Y axes and maximum sensitivity on any other axes. With some nuance: lowest in "vanilla" (280/208), increasing on the "A" variant (524/789), and maximum on The "X" version (1057/1092)... interesting fact is that "A" and "X" variant should have the same 12bit resolution.
One of the "X" card is used by my first joystick ( http://simhq.com/forum/ubbthreads.php/topics/3465416/My_first_diy_stick_Need_some_h.html#Post3465416 ), using the same Allegro A1302 and neodym magnet it reported 1074 steps on X and 1057 steps on Y axis. Back then I raised an eyebrow an moved along since over 1000 steps is excellent accuracy...and stick feels great too. Then I was thinking that if enough tweaking is applied sensitivity will increase accordingly, but now I'm not so sure anymore. Can really be obtained better values for X and Y axes??
If I've got acceptable values on BU0836 "simple" version, anything above 500 steps, it will be enough, but 208 is below my expectation.

I have 5 bodnar cards, 3 of them purchased last week, all of them behaving identicaly, so a malfunction is excluded. Can someone gave me any clue? Maybe someone else having a similar card can report his experience...

#3580481 - 05/26/12 08:17 PM Re: Hall sensor setup BU0836 [Re: Volans]  
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Volans Offline
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My sensors are wired like that:



So I use one magnet per sensor (like in julian265 guide)

How are your sensors setup? And what is your sensors reported sensitivity?

#3580786 - 05/27/12 11:49 AM Re: Hall sensor setup BU0836 [Re: Volans]  
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Volans Offline
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I tried the "bic pen" method (like in 'DIY hall sensor topic', a big THANKS to authors), using from smaller magnets to the powerful 10x15mm.
Same result: axes function is normal, but exactly the same sensitivity as above...tried with all the cards and with 2 pairs of hall sensors (A1302), just to be sure. Always low values on X and Y and maximum (normal) values on the other axes (1024 or 4096, depending on the card used)
Now I'm starting to feel a little sick..and dizzy....

Pictures of the original hall setup:




'Bic pen method' (simplified, for testing only)



8x8mm pair

10x15mm pair


I can't understand, clearly I miss something... Please, can some older owner of a Bodnar card to report his sensitivity values for X and Y axes?


Last edited by Volans; 05/27/12 11:59 AM.
#3581233 - 05/28/12 12:23 AM Re: Hall sensor setup BU0836 [Re: Volans]  
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oldbeamer2 Offline
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Volans, I spent some time holding the magnets in my hand and moving them around the sensor to work out where the high/low reading spots were. Then I visualized how the movement of the stick could be used to move the magnets to achieve the high/low readings I had observed manually.

Have you done that?

#3581284 - 05/28/12 02:34 AM Re: Hall sensor setup BU0836 [Re: Volans]  
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f15sim Offline
More projects than sense!
f15sim  Offline
More projects than sense!
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Graham, WA
Where did you get the "Precision Tester " application?

You might want to try using a single neodymium magnet with the bic pen body. I've been told by a builder that he gets a wider range of end points with that - I haven't tried that myself though.

g.


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#3581359 - 05/28/12 06:16 AM Re: Hall sensor setup BU0836 [Re: Volans]  
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oldbeamer2 Offline
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Just had another look at the photos. The sensor measures the magnetic field parallel to the FLAT face of the sensor, not the top. I think you may have been better off leaving the legs of the sensor straight.

#3581748 - 05/28/12 08:12 PM Re: Hall sensor setup BU0836 [Re: Volans]  
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Volans Offline
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Case solved!
Well, like they'll say, 'is the pilot, not the plane' attack, and that will be me feeling a bit stupid: only tried my sensors using this infamous 'precision tester'. The other software tester I'm using (for centering), DIView, will show sensitivity only when 'view raw data' is activated...and never did that before...
Clearly, I'm not an ace.
Real results (using my initial one magnet setup, like in the picture) are 1023 steps for Bodnar's 10bit cards and 4095 for 12bit cards. Mr Bodnar is back on my prayers.
In my defense I saw this 'precision tester' being extensively used on a big russian diy forum (sukhoy)...so I figured out...
All in all I've just spent 3 days reading a lot about hall sensor, searchin forums and opening a thread here, quite a fruitful activity
biggrin
A big thanks for all who tried to help me.

Oldbeamer: what you said is true, and my setup respect that: hall sensor is parallel with the magnetic field, and works perfectly. Different approaches.

Last edited by Volans; 05/28/12 08:20 PM.
#3581824 - 05/28/12 10:40 PM Re: Hall sensor setup BU0836 [Re: Volans]  
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oldbeamer2 Offline
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Melbourne, Australia
Well done! Please keep us posted on your progress.


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