Hacking Your Mouse To Fix The Misclick Of Doom
Wrapping Up
And that, folks, is how you hack a Trackman Marble to get rid of clicking glitches by making full use of its SPDT switches. The process should be very similar on any mouse utilizing similar hardware. The only mildly tricky part is figuring out how each switch gets read by the mouse's controller, particularly if it does something fancier than directly read whether the switch signal is high or low. It turned out slightly more complicated than I expected due to the odd circuitry on the left and right buttons tying into the PS/2 signals. But once that part got sorted out, the rest fell into place quickly enough. In the end, I would say the worst part of this little experiment was the tedious job of stripping and soldering over a dozen tiny wires.
When I gave the mouse a test-drive, all the button fussiness was gone. There were no misclicks or random drag-and-drop actions. It felt strange to have solid button behavior when my last memories of using the Trackman were so frustrating.
Was this all worthwhile? As a hobby or for curiosity's sake, it was a simple little project that I tackled mainly to prove that there is no reason for ancient switches to render your pointing device unusable due to contact bounce. For that purpose, I believe the project paid off, even though I doubt I'll use the Trackman for anything more than a spare.
Would I go through the hassle again? Probably not. After using the Trackman a bit for fun, I found that I did not like the left button's noticeably weaker feel. If I really wanted to repair this thing, I should have at least installed a new left button switch, though that would render my mod redundant. When my G500S' switches wear out, I'll be more inclined to simply replace the switches instead of modifying the PCB.
How about the total cost of my modification?
| Item | Cost |
|---|---|
| CD4043 | $1.00 |
| 2N3904 | $0.50 ($0.25 x 2) |
| Prototype board | $0.30 |
| Wires | $1.00 |
| Solder and other supplies | $1.00 |
| Labor | $100 |
| Total | $103.80 |
Financially, it makes little sense to bother with the repair unless you're trying to prove something to yourself. Repair costs that often exceed a replacement are the main reason why most consumer goods are rarely worth fixing. That doesn't change the fact that I am always annoyed when I run into easily preventable failures. The most expensive parts of my “perfect debounce” implementations are the SPDT switches, and those are already present, so there's no cost excuse to fall back on.
Are there any mouse manufacturers that use a variant of my SPDT debounce implementations? If not, I hope this little bit of increased consumer awareness will motivate manufacturers to do the right thing and implement one of these penny-scale fixes. There is no patent excuse for not doing so, since these techniques have been known for decades. I hadn't read through TI's CD4043's datasheet beyond the pin-out initially, but when I revisited the document to check something else, I noticed that SPDT debouncing is even given as an example application, albeit with 1MΩ resistors instead of the 10kΩ I used.
I would gladly pay $5 more for a mouse that offers lifetime glitch-free buttons over an otherwise identical model that doesn't. How much would such a feature be worth to you?
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Daniel Sauvageau is a Contributing Writer for Tom's Hardware. Follow him on Twitter and Google+.
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You give me too much credit. This is a simple hack once you know what you are dealing with - finding out what you have to work with is usually the most tedious part of a modification job, especially when you don't have design schematics or someone else's instructions to start from.
The hack might be more trouble than it is worth but it does show that there is no reason for mouse buttons with SPDT switches to glitch until the switch mechanically fails. Other than mice manufacturers choosing to design them this that way that is.
My G500S is about four years old and the glitching is at that early stage where I'm not sure if the glitches are caused by the mouse or by mouse movement when I click.
Problem solved.
The switches can be magnetically shielded, and as long as the button actuation functions (no broken springs), the button will continue to work, along with any vibrations of the actuation being calibrated out in software.
I doubt switches that require additional calibration steps would be popular in a market where manufacturers are trying to optimize every penny of profit they think they can get away with out of their product.
One option which does not require calibration is optical sensing: poke a slotted stem through the detector. Most mechanical mice used optical wheel encoders to convert ball motion to digital. The same thing could be done for switches.
I doubt either option would be as inexpensive as a mechanical switch and with the "memory" version of my hack, it would be a practically free fix. Free is a tough price to beat.
I'll take one of those please.
It would be nice to hear back from the likes of Logitech or Microsoft about why they appear not to have implemented a proper de-bounce circuit of this type and when they intend to do so!
im so sick of mice wearing out, you finally found the perfect mouse, then 4-5 years later it dies, and you are on the hunt again because that model is no longer in production, and quality took a nose dive while you were away.
The mouse is now about 7 years old and still great
It's unlikely that this would happen in most industries, it's just not worth the effort in most cases. It's hard enough to design and manufacture a reliable, durable bug-free product as it is. It's just not worth the trouble/risk to introduce precise failures into the product. Market research might tell you the average usage patterns, allowing you to calibrate a component to fail, on average, a few weeks after the warranty period. But if you miscalculate, then you're looking at lots of products failing before the warranty period expires. Also, there's no guarantee that people will replace a broken mouse with another from the same company. If this were common practice, it would be very easy for a manufacturer to buck the trend and, without increasing their price or costs, produce a product that is far more reliable than any others on the market. Such a company would then enjoy the higher frequency of mice replacement built into their competitors' products as well as being viewed as higher quality than competing brands.