This page contains answers to commonly-asked questions.



General Questions


  1. It used to work, but then I loaded something using a programmer, and it no longer works.

    Review the instructions.


  2. I tested your device for accuracy and it's not as accurate as you say.

    Do not attempt to calibrate the magnetometer near metal. In most cases you cannot be inside. Watch out for metal buried in the ground. You also must align the laser correctly to take accurate survey measurements.


  3. I applied the wrong voltage or re-wired the battery wrong and the device no longer functions

    I am not responsible for these mistakes, however I have applied reverse polarity power and the components tolerated it and did not fail though they did draw a lot of current. There is no protection on the boards for this.


  4. I know how to do schematic layout, and I would like to improve your layout.

    Great, please send it to me when you are done.


  5. I found some problems with your schematics.

    Great, please inform me of them.


  6. I am using an operating system which you do not provide binaries for, and the source code won't compile.

    Sorry I can only support linux and freebsd. I have binaries for windows, but don't expect frequent updates. Feel free to send me your build errors.


  7. I am using linux, and sometimes I cannot get the device to work via usb, I see these errors via dmesg. 
    usb 1-1: new full speed USB device using uhci_hcd and address 52
usb 1-1: device descriptor read/64, error -110

    This is a bug in the linux usb drivers. For now if you unload and reload the uhci_hcd kernel module, the device will work again. Alternately you can powercycle the device 20-30 times. Hopefully with newer versions of linux (than 2.6.24) this problem will be solved.


  8. How does the device automatically calibrate?

    This is a complicated process and is covered in detail; see the calibration documentation.


  9. The the device is wrong, it isn't pointing north.

    The device must be calibrated to work correctly. Also note that the device points to magnetic north by default. True north mode can be configured, declination calibration (See: variation magnetic.gif) must be correct.


  10. Your website sucks, it looks like it was made by an 8 year-old

    Please make me a better website, send it to me when you are done.


  11. I want to resell these devices.

    Great, contact me and I would love to sell you units to resell with a special discount.


  12. I can manufacture and sell these devices. Do I have to pay you royalties even though you have no direct part in my activites?

    No, please make as many as you like. You only have to pay me if I do work for you or provide you with hardware. If you choose to use my schematics and software, your use is subject to the terms of the GPL.


  13. Do you have a patent?

    No, my goal is to benefit as many people as possible. A patent would deny others from making similar products, these products could potentially benefit more people than my own product. My ideas cannot be patented.


Pointer Device


  1. How sensitive is the pointer device to movement?

    With filtering the sensors give me better resolution than the typical human hand can actuate the device, therefore any improvement to sensitivity would have limited benefit. I find it easy to move the mouse to any pixel on a 1280 wide screen with 90 degrees of rotation over the 1280 pixels.


  2. How am I supposed to use this thing?

    To move up and down is intuitive. If you are near the equator, aim to the left and right to move to the left and right, if you are a bit north or south of the equator, roll the device to to the left or right.


  3. The mouse does little circles, why isn't it still?

    You likely have magnetic interference from nearby electronics.


  4. I am running 64bit windows and I cannot communicate with the device.

    Windows 64 is even worse than normal windows. They don't support generic drivers. Right now you will have to not use windows 64, or let me know if you find a workaround.


  5. What does it mean if there is an X carved in the back of my pointer device?

    The accelerometer is difficult to solder, therefore there are some units which the accelerometer was destroyed in assembly. If your device is marked with an X, then the device only has working magnetic sensors, and cannot do tilt-compensation.


  6. I am having trouble double clicking because I cannot hold the device still enough.

    Press the bottom button then the left button will double click.


  7. I see that the right and left buttons right and left click, but the bottom button enables scrolling, how do I middle click?

    Press the bottom button then right soon after to middle click.


  8. The device is configured to mouse only, how do get to cdc-serial mode where I can configure the device?

    Hold the right button down at powerup, this will revert to cdc-serial mode.


  9. I am using windows, why can't I use cdc-serial and mouse at the same time?

    I'm sorry you are using windows. Windows does not comply with the usb standards. This is because Microsoft likes to break standards on purpose. I have decided that I can only offer windows users either cdc-serial mode, mouse, or joystick mode, but only one at a time. If you try to configure multiple modes then access the device using a windows computer, the device will not work because I don't provide a driver, if I did, it would crash your computer. You can always hold key 2 down when plugging the device in and it will revert to cdc-serial only so that you can configure it.


  10. How does the pointer device calculate the movement for the mouse?

    The pointer device uses the earth's magnetic field to calculate the orientation of the device. The magnetic field is actually a vector which is pointed toward the earth at the declination (varies with lattitude, See dip_magnetic.gif) The device measures the direction of this vector, and from this can calculate two angles of rotation. There is no way to calculate the rotation around this vector using only magnetic sensors which is why the pointer does not move when you rotate around the direction of the magnetic field. If you really want to know the details, take a look at mouse.c in the source code.


  11. I want to use the uart, how do I do this?

    The uart is like a regular computer's serial port, except it runs at 3v. There are vias on the board labled for this purpose. You can connect it to a regulator using a tranceiver with a voltage pump (max3232) You can hold key 2 down at startup to force the device to enable the uart. The default baud rate is 38400. Once communicating you can set the uart to be enabled normally as well as the baud rate.