Quote from: Shmalzbrot

What would be the effort to send 5 different mouse buttons? Do you need driver support for that? Would it be possible to fool an existing driver?

Quote from: Shmalzbrot

Have you calculated the force being applied on the BTUs? A 52mm Ball will weigh around 100grams (tested a Logitech Marble FX ball), my relaxed Fingers laying on the ball add another 150grams. At the angle the BTUs are positioned, I figure you're pretty close to the max rated load of the Polymer ball type, especially if you consider additional forces from moving the ball.

Quote from: Shmalzbrot

Have you considered that the "natural" X/Y axis (the directions a user intuitively moves the ball to go straight left/right and up/down ) do not correspond to the physical X/Y axis of the sensor? Have you considered that the natural X/Y axis might not be perpendicular? I.e. are you planning to implement a translation from physical coordinates to actual mouse movement? Are you planning to add some kind of calibration to account for the different natural movement directions of different users? [...] Also, the way I use an ergonomical trackball, the actual center of movement (where physical movement and desired mouse movement would differ the least) is towards my hand - incidentally very close to where the sensor of the TBE sits

Quote from: Shmalzbrot

PLEASE don't put a sensor underneath the ball - if you care about ergonomic design, you want the trackball to be as low as possible. Every mm of height adds bend+strain to your wrist and/or reduces the contact area of your arm, increasing pressure on your heel of hand. Also, if you need to translate physical movement to mouse cursor movement anyway, it does not matter where the sensor is placed.

Hi Shmalzbrot,Welcome to geekhack! Sorry about my own lack of progress working on trackballs; Ive gotten stuck on several other unrelated projects (both keyboard related and otherwise) in the last few months.Ill tell you about some of my personal goals, but note those may be different from other peoples goals. My main goal with a trackball project will be to build something that is in between two keyboard halves, part of the same chassis. The goal is to have something very easy to reach by either hand without reaching far from standard typing position. This is a somewhat different goal from a standalone trackball where someone would have their hand on it continuously for hours at a time. I dont personally really care about the palmrest part at all, because the way I type, my palms/wrists are floating above the keyboard surface, not resting on anything. With a trackball, it will be the same. I plan to simply use regular keyboard keys (probably on the other hand from the one manipulating the trackball) as mouse buttons, so button placement, etc. is also not really among my concerns.Were I to design a standalone trackball, Id recommend resting the hand tilted at a 40°+ angle if possible (to avoid excessive hand pronation). Any permanent palmrest should mostly support the side of the hand (the part below the pinky finger), rather than the center of the palm (this avoids pressure on the carpal tunnel). Id personally try to use keyswitches with slightly longer travel than a typical mouse switch (on order 1.52mm, with maybe .5mm of pre-actuation travel and 1mm+ of post-actuation travel). I personally think mouse buttons are awful, and mainly get used because theyre what people are used to and expect, rather than any particular merit.That shouldnt be much trouble, once the firmware has a reasonable USB HID implementation. Sending mouse buttons, keyboard combinations, game controller inputs, or whatever else should be pretty straightforward. Figuring out the best system for configuring the firmware to do what you want is an interesting non-trivial problem, though. The user interface design part is the difficult problem here though, not actually coding up the mouse button actions.Which ball transfer units are you considering? The ones I got some samples of from Synnöve have a metal ball, and seem quite sturdy. I havent subjected any to long-term usage, so I cant tell you for sure how well theyll hold up, but I have high hopes.Absolutely. Personally, my goal is to use two sensors, and as an intermediate step compute the full 3-dimensional rotation of the ball at each timestep (e.g. as a quaternion). Once you have a precise/accurate measure of the 3-d rotation of the ball, its fairly easy to transform that to find the rotation relative to any particular set of axes, which means any arbitrary ball directions could be associated with X and Y (even with different sensitivity in each dimension if you want), when you want to use the ball motion to move a 2-d cursor.Note that on a one-sensor trackball, the center of movement on the ball is the point directly opposite the sensor. The TBE has its sensor a bit behind the bottom center of the ball, which means that on the opposite side, at the top of the ball, the center of motion is actually quite substantially in front of the top of the ball. If youve learned to correctly move the ball despite yourself putting your hand on the nearer-than-center part of the ball, that just means youve learned to compensate for the specific way the TBE moves. The sensor is actually in a very suboptimal place given your description of your hands resting position.A separate scroll wheel should be entirely unnecessary if the whole ball can be used for scrolling while some button is held down.My personal advice would be to avoid flexing or extending your wrist at all if possible, keeping it in a neutral position, and also avoid putting pressure on the heel of your hand to the extent possible. Having your palm and wrist entirely in the air is the ideal, but resting it lightly on some surface is probably acceptable, as long as youre not pressing down hard. Of critical importance is the height of your desk and chair, and the distance to the trackball.