Mouse Brains Plus Line Laser Equals Rangefinder

[Neumi] wrote in with a sweet robotics hack. It’s a 2D laser distance sensor (YouTube) made with a cheap line laser and an optical mouse’s flow-sensor chip used as a low-resolution camera. In one sense, it’s a standard laser-distance-sensor project. But it is clever for a whole bunch of reasons.


For one, using a mouse sensor as a low-res camera is awesome. It’s designed to read from a standard red LED, so the sensitivity is in just the right ballpark for use with a line laser. It returns a 30×30 pixel greyscale image, which is just about the right amount of data for a low-end microcontroller to handle and keep up with the framerate without resorting to coding tricks.

It’s also no coincidence that these sensors are available with lenses built in, for relatively cheap, on eBay. Apparently the quadcopter gurus use them as if they were mice to visually track their quad’s motion. Hacker spillover!

Detecting the laser line as it reflects off of whatever objects are lying on [Neumi]’s floor could also possibly prove difficult, and might produce false readings in the presence of background illumination. So [Neumi] takes two readings with the camera — one with the laser on and one with it off — and differences them. Done fast enough, this should reduce any non-laser sources down to the sensor’s noise floor. Finally, there’s some thresholding and averaging going on behind the scenes that help make everything work out right. The code is up on GitHub.

Not a bad build for a 2D laser distance system on a budget. If you want to shell out a bit more money, and are into a seriously involved build, this is probably the slickest we’ve seen in a long time. And if you’re thinking that you’ve heard of [Neumi] before, you’re right: we featured this 405mm laser PCB exposer / burner CNC machine just a few months ago.

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Mouse Pen from Old Parts

No offense to [Douglas Engelbart] but the computer mouse has always seemed a bit of a hack to us (and not in the good sense of the word). Sure we’ve all gotten used to them, but unlike a computer keyboard, there is no pre-computer analog to a mouse. There are plenty of alternatives, of course, like touchpads and trackballs, but they never seem to catch on to the extent that the plain old mouse has.

One interesting variation is the pen mouse. These do rely on a pre-computer analog: a pen or pencil. You can buy them already made (and they are surprisingly inexpensive), but what fun is that? [MikB] wanted one and decided to build it instead of buying it.

The main parts of the pen mouse include a cheap mouse with a failing scroll wheel, a bingo pen, and the base from an old web camera. There’s also a normal-sized pen to act as the handpiece. The project is mostly mechanical rather than electrical. [MikB] took the mouse apart and cut the PCB to fit inside the base. The rest of the build is a construction project.

The result appears to work well. [MikB] includes instructions for installing the mouse correctly in Linux. The net effect is like a tablet but doesn’t’ require much space on your desk. We’ve seen plenty of mouse projects in the past, of course. We’ve even seen hacks for a head mouse if that’s your thing.

Rapid Fire Mod For A Wireless Mouse

Rapid Fire Wireless Mouse

Sometimes changing your computer mouse can be uncomfortable for a while until you get used to the replacement. It may also take some time to get used to new features or the lack of features the new mouse has. [Jon] bought an awesome wireless mouse that he really likes but it is missing one critical feature: rapid fire for gaming. He previously modded his old wired mouse to have a rapid fire button using a 555 timer. That worked fine as the mouse ran off the USB’s 5 volts, and that’s the voltage the 555 timer needed. The new wireless mouse has a 1.5 volt battery and can not support the 555 timer. What’s a gamer to do?

[Jon] searched around the ‘net but could not find any wireless rapid fire mods. Eventually, he did find a low-voltage variation called the LMC555 and ordered a few for his project. The new wireless mouse was taken apart in order to find out how the mouse buttons work. In this case, the signal pin is pulled low when the mouse button is pushed. Now that it is known how the mouse button works, just a couple of resistors, a capacitor, an NPN transistor and a push button switch are all that are necessary to finish up this mod. When the push button is pressed, the LMC555 timer activates the transistor in order to ground the mouse button signal pin. This happens to the tune of 1236 times a minute! That is a lot of rapid firing.

The few components were soldered up neatly and packed into the limited spare area inside the mouse. A hole drilled in the side of the mouse’s housing holds the new rapid fire push button in an ergonomically pleasing location.

Earlier, we mentioned [Jon] has done this mod before on a wired mouse. He learned about that project here on Hackaday. Check it out if your wired mouse is craving a rapid fire button.

Video after the break…

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Malware In A Mouse

Keyloggers, in both hardware and software forms, have been around for a long, long time. More devious keyloggers are smart enough to ‘type’ commands into a computer and install Trojans, back doors, and other really nasty stuff. What about mice, though? Surely there’s no way the humble USB mouse could become an avenue of attack for some crazy security shenanigans, right?

As it turns out, yes, breaking into a computer with nothing but a USB mouse is possible. The folks over at CT Magazine, the preeminent German computer rag, have made the Trojan mouse (German, terrible Google translation)

The only input a mouse receives are button presses, scroll wheel ticks, and the view from a tiny, crappy camera embedded in the base. The build reads this camera with an Arduino, and when a certain pattern of gray and grayer pixels appear, it triggers a command to download a file from the Internet. From there, and from a security standpoint, Bob’s your uncle.

Looking through the camera inside a mouse is nothing new; it’s been done over the Internet and turned into the worst scanner ever made. Still, being able to process that image data and do something with it is very cool. Just don’t accept mouse pads from strangers.

Danke [Ianmcmill] for the tip.

Your Mouse Is A Terrible Webcam


It should come as no surprise your optical mouse contains a very tiny, very low resolution camera. [Franci] decided to take apart one of his old mice and turn that tiny optical sensor into a webcam.

Inside [Franci]’s Logitech RX 250 is an ADNS-5020 optical sensor. This three wire SPI device stuffed into an 8-pin package is a 15×15 pixel grayscale image sensor. [Franci] started this project by bringing out the Arduino and Ethernet shield. After soldering a pull-up resistor to the image sensor’s reset pin, connecting the rest of the circuit was as simple as soldering a few wires to the Arduino.

The Arduino sketch sends the image data for each pixel to a computer over a serial connection. A bit of javascript and a touch of HTML takes this pixel data and turns it into a webpage with a live view of whatever is directly under [Franci]’s mouse.

Video of the mousewebcam in action below.

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Building a hard drive scratch controller


If you’re reading this blog then chances are you have a dead hard drive hanging out somewhere in your house. Here’s a weekend project that will put it back into use. [Andreas] took on the popular project which combines a hard drive and optical mouse to build a scratch controller.

The gist of the build is that you use an optical mouse sensor to track the movement of the platter. But [Andreas] made things harder on himself by not using the USB capability of the mouse and mapping it in software for his needs. Instead he plucked the sensor from the mouse, reading it using an Arduino. After much trial and error with the best way to coat the underside of the platter to play nicely with the sensor he managed to get it up and running. The controller issues commands using the MIDI protocol, forming a strong foundation for future upgrades which could lead to a full-blown DJ console hack.

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Tube radio husk gets a web radio transplant

[Dominic Buchstaller] found this German Greatz tube radio at a flea market. It only cost him about €35 and was in a bit more rough condition than the finished product you see above. He also found that a portion of the original circuitry was missing, making it completely non-function. He cleaned up the case to improve the wife-acceptance-factor, and outfitted it with hardware to make it a web radio.

Adding modern speakers was pretty easy as he was already replacing the original cloth bezel which has several holes and tears in it. A set of elements from some Logitech computer speakers served as the organ donors for this step in the process. As he was trying to keep a stock look he came up with a really neat hack to use the original knobs. The station select happens to have a large metal wheel on the inside which is about a centimeter wide. [Dominic] used the optical sensor from a mouse to monitor the turning of the dial by aiming the sensor at this wheel. Internet connectivity was provided by a wireless router he had on hand. This way he can stream music or play from an SD card he also used in the retrofit.