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Topic: Arduino and compass (Read 9003 times) previous topic - next topic



A small digital compass based on hall effect is connected to an Arduino 10000 board. The logic in the board turns on and off leds depending on direction. There are 4 leds, one for each in N,S,W,E. When two leds are ON the direction is in the middle (es. NW). The digital compass chip (the white cylinder) comes from http://www.dinsmoresensors.com/ and costs 10$. The use of Arduino Bluetooth may support compass for smart phones.


Cool! Now buy some of those tiny, button-size vibrating things from sparkfun.com, put them in a belt and connect them to the Arduino so that the vibrator (ha ha ::)) that faces north vibrates. Wear it at all times for a week or three, and see how your perception of space and your "room feeling" changes. ;)



Exactly a project I've been thinking about.

I've ordered my vibrating motors from Sparkfun but the order page for the compass returns a "not found."

I've sent them an email but does anyone know of a source for this part with online ordering?



Aug 15, 2008, 06:28 pm Last Edit: Aug 15, 2008, 06:33 pm by BroHogan Reason: 1

Sparkfun's compass page is http://www.sparkfun.com/commerce/categories.php?c=83 but there are cheaper alternatives. dadista's is one, and there's also the HM55B from Parallex.

If your planning something wearable you might consider the Lilypad. (Sparkfun also sells the vibrator in a Lilypad format.) http://www.sparkfun.com/commerce/categories.php?c=135

Thanks to PlastBox for bringing up that interesting subject.
"Data is not information, information is not knowledge, knowledge is not understanding, understanding is not wisdom."
~ Clifford Stoll


Thanks, BroHogan.

I've seen the compasses at Sparkfun and will order one from there if I can't source the $10 part.

I've gotten an email back from the sensor company but it was just a pointer to the data sheet. I've emailed them again pointing out that I'd like to buy something if they'll give me a way to do so.


FYI, I never got a return email from the sensor company so I called and ordered the part by phone.

In quantities of one it is $15 + $5 shipping.

I'll let you know how the project turns out.


Please do, Ronn! ;D

Always been very intrigued bu sensory substitution and such, as every experiment I've seen shows that the brain in very little time adopts new sensory input (like a compass) so long as movement of the body and the other senses correspond with the input from the new sense.

Will be exciting to see what you learn!


Yes, depending on the results of this little experiment, it would be interesting to continue to add other sensors.

An arts group did some really interesting work with 360 degree proximity sensors driving vibration motors. You can't sneak up on someone who can sense objects all around them, including behind.

Still watching the mailbox.


Aug 18, 2008, 12:38 pm Last Edit: Aug 18, 2008, 12:44 pm by PlastBox Reason: 1
You mean these guys? http://www.k2.t.u-tokyo.ac.jp/perception/HapticRadar/index-e.html

Myself, I bought 3 ultrasound sensors and vibrators from sparkfun but I never got around to figuring out how to sync the sensors so they don't interfere with eachother. The sensors also have a range of 6 meters which is way more than I need or want but that could be overcome with programming.

Amongst the projects I have concidered are
- the compass belt
- proxy sensor halo
- something akin to a magnet/electromagnetic field sensor, simply coupled to a single vibrator on my skin. Does anyone know of any sensors that would pick up electromagnetic fields? Like, those produced around mains wireing, computers, etc.
- a silicone fingertip embedded with 1 force sensor and a grid to detect amount of pressure as well as some location data, for experimentation on my stepdad who lost half his left index finger at work a few years back. Each point in the grid would be coupled to a vibrators ON/OFF status, while the force sensor decides how strongly the active feedback-points would vibrate.
- 2 microphones coupled with band-pass filters (or somesuch) to direct diffrent frequency ranges into several vibrators on a subjects skin (for increased resolution and the ability to "hear" high-, medium- and low-pitched sounds at the same time) for a friend of mine who was born deaf. She has the most incredible, mindblowing sensitivity to vibration, so I have no doubt a wellmade system like this one could at least let her "hear" if a car is running nearby, or if a cellphone is bleeping away. Perhaps, with practice, even learn to differentiate between such things as different (simple) ringtones and with 2 microphones and sets of feedback-devices maybe learn to sense at least the general direction of the origin of the sound.

Also, I have, many times, pondred why on earth simple feedback devices aren't implemented in prostetics?! I mean, a force sensor or a flex sensor costs next to nothing compared to the price of the prostetic itself and considering the fact that lack of feedback is something all prostetic users complain about, I find it incredibly strange that it isn't used!

I mean, when a Lego robot can quite easily be equiped with the sensors needed to pick up a whimsy plastic cup or a raw egg without breaking them, why should that be a problem for people who pay out their arse for equipment they need..?


Yes, those are the guys.

Thank you for your additional ideas and, in particular, some of the reasons for your interest in this area. Fascinating.

I'm thinking of using a hat for my compass rig. I think it might feel more natural to sense direction relative to the direction of your gaze rather than the orientation of your body. It would also be easier to fit on other people quickly to let them experience the effect.  It would be nice to make it self contained but I haven't started looking at power requirements yet. Even if I don't have wires snaking out of my shirt or down my back, this isn't something I'd want to try to carry past the TSA.

For a _very_ simple, if invasive, approach to electromagnetic sensing, have a look here: http://www.wired.com/gadgets/mods/news/2006/06/71087

As to your question about prosthetic feedback, could it be a matter of entrenched technology? There's a long history of "dumb" prosthetics and research is leading to fully active limbs with movement and feedback. Maybe anyone who would be working on a simple feedback mechanism is working, instead, on active prosthetics?


Heh, I've seen the whole magnet-in-fingertip deal before and although it is very very cool, I'd probably not do it unless someone found a way to ensure the magnet doesn't break after a while.

The hat idea sounds reasonable.. I guess it would make sense to get your newfound sense of direction from your head instead of your waist. =P Get a fancy pimp-hat, with a bit of room around the head. You could probably make room for a Boarduino, your sensor and a 9V battery in there, and stuff some vibrators into the lining where they touch your head.

I've been seeing some pretty cool prostetics on the horizon lately. Perhaps the coolest is the one where a doctor grafted the cut nerves that would go to the arm onto different parts of the chest muscle, then used emg-sensors to monitor the chestmuscle and pick up when the user wanted to bend or straighten his arm, or lift it, or a number of other things. Still not exactly top of the pops with what science should be able to produce today but still a great deal better than those retarded harness and cable hooks most people are forced to use. =P


The compass in the hat idea is why I suggested the Lilypad. With conductive thread it would be a pretty clean implimentation. Of course a prototype could use any Arduino.

All the best to the both of you in this project.
"Data is not information, information is not knowledge, knowledge is not understanding, understanding is not wisdom."
~ Clifford Stoll



I'll be prototyping with a Boarduino. We'll see after that.

I may have to rethink the pure headmount approach, even if I put the vibrating motors in a hat. This sensor only allows for 12 degrees of tilt and I certainly tilt my head more than that in various directions.  There are sensors that have better tilt compensation but, this is just a proof-of-concept.


I love the direction sensing hat idea. I can imagine how nice it would be while mountain biking to always know which way North is. If I build one, it will be in a cycling helmet! As for excess tilt, just disable the feedback when the hat is tilted too far. That way you avoid false readings. The wearer would quickly learn to glance at the horizon to get a direction update.

Some of us can say which way is North all the time without any assistance from a compass. The rest of us would love to have that ability. I guess there is also a 3rd group who don't care either way. (ha ha)


... As for excess tilt, just disable the feedback when the hat is tilted too far. That way you avoid false readings. ...

Excellent idea! And when you take it off and toss it on the table, it turns itself off, saving batteries.  :)

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