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Topic: magnetic mouse whichsensor? (Read 179 times) previous topic - next topic

slipsoftware

I have a good programming background but im very new to sensors  and microcontrollers. I have a need and desire to make a magnetic mouse. I have seen some 3 axis magnetic sensors online but I am unsure which one to purchase. The majority of these are bundled with a gyroscope. so most of the community focuses around the gyroscopes for drones and less around the magnetic sensor. Some of them seem to operate more like a joystick  and less like a mouse. I need it to detect just like a mouse would not just the direction but the speed at witch it moves and if it moves off the sensor it needs to still detect the magnetic field moving away or coming towards it otherwise it would give a very small area to operate a mouse within. thank you for your time

Koepel

Can you make a picture ? Because I don't understand how this could work.

With a single magnet and a few hall sensors, a joystick can be made. I think they existed already 10 or 20 years ago.
Some pen and tablets use a grid with inductive coupling.

How far away from the magnet do you want the mouse to work ? A large neodymium magnet can be dangerous. Should someone take off their watch to use the mouse ? Perhaps you can keep a spatula nearby in case someone is stuck to the magnet with something metal.

The most used sensor for a compass is a HMC5883L, you can buy one to see for yourself what it can do. It is sensitive for metals and wires with current and electrical devices, just like a normal compass.

slipsoftware

I want the mouse to work like a standard mouse.  but without direct contact to the surface below and an added z axis. So essentially if I put a 1 mm magnet on the end of a pen I could control xyz as if I was using a mouse/stylus with the bonus z axis but It needs to be done with no surface contact. 

I was looking at the compass sensors earlier but I was not sure if they could be used for this application. A compass in my mind only returns  a direction/coordinate that would work for a joystick with no variable speed but not a mouse .Do the compass sensors  have the ability to track the speed at which a conductive material is moving in a direction?

Koepel

I'm sorry, but I have no clue how to make a mouse that way.

When a grid with many magnetometers (compass sensors) is used, then a pen with a magnet could be used above it, and some 3D xyz information can be calculated. I think it will be very inaccurate.

Do you want a sensor that measures the speed of a magnet ? That sounds very strange to me. I can't even think of a sensor that measures the speed. A sensor can measure acceleration or two positions and calculate the speed.

The magnetometers measures the magnetic field strength in three axis. In theory it is possible to use a single magnet and a single sensor to determine the position of the magnet. I think that will only work when one of the magnetic poles (north or south) of the magnet is always pointing to the sensor. When the magnet is kept horizontal, it is in my opinion impossible to determine its position with a single magnetometer.

You could try to search for a patent that uses it.

If you want to try something, you could buy four magnetometers and put them in the corners of a mouse pad. Use a magnet above it and see if you can do something with that data. You will have 4 * 3 axis, that is 12 values. I don't see it how that data could be used, but it could be a fun experiment.

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