KVM Foot Switch In A Few Steps

August 12, 2019 by Kristina Panos 6 Comments

[Radishmouse], despite the handle, is not a mouse guy. Give him a keyboard and he will get around just fine in any OS or program. As it is, he’s got a handful of ThinkPads, each running a different OS. He wanted to be able to switch his nice mechanical keyboard between two laptops without the hassle of unplugging and replugging the thing. His solution: a DIY KVM foot switch.

He’s been learning about electronics and 3D design, and this problem was the perfect opportunity to dig in and get his hands dirty. After learning enough about the USB protocol and switches to figure out what had to happen, he made a prototype from a pâte tub. Though undeniably classy, this vessel would never survive the rigors of foot-stomping in feline territory. Fortunately, [radishmouse] has also been learning about 3D design. After some trial and error, he came up with a sturdy, curvy 3D-printed two-piece enclosure. We particularly like the blocks built into the bottom piece that shore up the USB ports.

There are lots of reasons to build input controls for those under-utilized appendages at the ends of your legs. You could control your ‘scope with a probe in each hand, or use a foot switch to relocate an inconvenient power button.

Via [r/functionalprint]

From A Dead Laptop To A Portable KVM And PiTop

March 10, 2019 by Jenny List 14 Comments

An essential tool of many sysadmins is a portable terminal ready to plug into an ailing rack-mounted server to administer first aid. At their simplest, they are simply a monitor and keyboard on a trolley, but more often they will be a laptop pre-loaded with tools for the purpose. Sysadmins will hang on tenaciously to now-ancient laptops for this application because they possess a hardware serial port.

[Frank Adams] has taken a different route with his emergency server crash cart, because while he’s used an old laptop he hasn’t hung onto it for its original hardware. Instead, he’s used a Teensy and an LVDS driver board to replace the motherboards of two old Dell Latitude laptops, one of which is a simple KVM device and the other of which is a laptop in its own right featuring a Raspberry Pi 3. He’s produced a video as well, which we’ve placed below the break.

There was a time when laptop display panels were seen as unhackable, but the advent of cheap driver boards has meant that conversions such as this one have become a relatively well-worn path. The job he’s done here is a particularly well-executed one though, making good use of the generous amount of space to be found in an older business-class laptop. There isn’t a battery because this application doesn’t demand one, however, with the battery compartment intact it does not seem impossible that a suitable charger/monitor board could be included along with a boost converter to provide his 12V supply.

This isn’t the first Pi laptop in a re-used commercial machine’s case we’ve seen, there was also this Sony Vaio.

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Twin Pis For Remote Computer Management

November 5, 2017 by Lewin Day 32 Comments

Sometimes you have a whole bunch of computers that you need to work with, and having a keyboard, monitor, and mouse for each one becomes too much to deal with. There are a multitude of solutions to this problem, but [Fmstrat] went the hacker route, and built their own.

The build is a rather unique way of controlling PCs remotely, but it does the job. A Raspberry Pi 3 is pressed into service as the core of the operation. It’s accessible over IP for remote control. Video is captured from the controlled machines through the combination of an HDMI-to-S-Video adapter and an analog video capture card plugged into the Pi. Keystrokes are sent in a roundabout way, first sent to a Pi Zero over a USB-to-Serial adapter. From there, the Pi acts as an emulated mouse and keyboard to the PC under control.

One caveat of remotely controlling computers over a network is that if things go pearshaped, it can become necessary to power cycle the machine. [Fmstrat] deals with this by fitting a relay board to the Pi 3, which is connected to the reset buttons of the machines under control.

It may not be the quickest, easiest, or industry standard way of controlling remote computers, but it works. [Fmstrat] tells us this build was primarily designed to get around the fact that there aren’t any decent cheap IP-KVM systems, and consumer motherboards don’t support the IPMI standard that would otherwise be useful here.

We particularly like the hard-wired relays for rebooting a machine – great for when a network dropout is stopping Wake-on-LAN packets from achieving their goal. While the conversion of HDMI outputs into analog video for capture is unusual and somewhat costly on a per-machine basis, it’s functional and gives the system the ability to work with any machine capable of outputting a basic analog video signal. With the Pi Zero keyboard emulation and analog video capture, we could see this being used with everything from modern computers to vintage 80s hardware. If you’ve ever needed to control an Amiga 2000 remotely for whatever reason, this could be the way to do it.

We’ve seen plenty of other KVM builds over the years, too – like this low-cost HDMI switcher.

Hackaday Prize Entry: Low Cost KVM

August 5, 2017 by Brian Benchoff 30 Comments

Back in the old days, when handing someone a DB serial cable when they asked for a DE serial cable would get you killed, KVM switchers were a thing. These devices were simple boxes with a few VGA ports, a few PS/2 ports, and a button or dial that allowed your input (keyboard and mouse) and output (video) to be used with multiple computers. Early KVMs were really just a big ‘ol rotary switch with far, far too many poles. Do you remember that PS/2 wasn’t able to be hot plugged? The designers of these KVMs never knew that.

Today, KVM switchers are a bit more complicated than a simple rotary switch. We’re not dealing with VGA anymore — we have HDMI muxes. We’re also not dealing with PS/2 anymore, and USB requires a bit of microelectronics to switch from one computer to another. For one of his many Hackaday Prize entries, [KC Lee] is designing a low-cost HDMI switch and USB mux. It works, it’s cheap, and if you need to switch a keyboard, mouse, and monitor between boxes, it’s exactly what you need.

First off, the HDMI switching. Designing a switch for HDMI would usually take some obscure parts, intricate routing, and a lot of prototyping time. [KC] found a way around this: just hack up a $5 HDMI switch. This cheap HDMI switch is as simple as it gets, with an HDMI mux doing the heavy lifting and an 8-pin microcontroller to handle the buttons and a selector LED.

For the USB, there are a few more design choices. For USB 1.x switching, [KC] figures he can get away with a 74HC4052 dual 4:1 analog mux. Yes, he’s doing digital with analog chips, the heathen. There are drawbacks to this: everything could break, and it’s only USB 1.x, anyway. For a USB 2.0 KVM, there are a few more professional options. The OnSemi NCN9252 is a proper USB 2.0 mux, and in the current design.

Hacking A KVM: Teach A Keyboard Switch To Spy

August 8, 2015 by Mike Szczys 11 Comments

When it comes to large systems, there are a lot more computers than there are people maintaining them. That’s not a big deal since you can simply use a KVM to connect one Keyboard/Video/Mouse terminal up to all of them, switching between each box simply and seamlessly. The side effect is that now the KVM has just as much access to all of those systems as the human who caresses the keyboard. [Yaniv Balmas] and [Lior Oppenheim] spent some time reverse engineering the firmware for one of these devices and demonstrated how shady firmware can pwn these systems, even when some of the systems themselves are air-gapped from the Internet. This was their first DEF CON talk and they did a great job of explaining what it took to hack these devices.

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BeagleBones And Teensies Become KVMs

June 25, 2015 by Brian Benchoff 41 Comments

[pmf], like most of us, I’m sure, spends most of his days on a computer. He also has a smartphone he keeps at his side, but over the years he’s grown accustomed to typing on a real keyboard. He came up with the idea of making a USB switch that would allow his keyboard to control either his computer or his phone, and hit upon a really neat way of doing it. He’s using a BeagleBone Black and a Teensy to switch his keyboard between his computer and his phone with just a press of a button.

This homebrew smart KVM uses a BeagleBone Black for most of the heavy lifting. A keyboard and mouse is connected to the USB host port of the BeagleBone, and the main computer is connected to the device port. The BeagleBone is set up to pass through the USB keyboard and mouse to the computer with the help of what Linux calls a ‘gadget’ driver. This required an update to the Linux 4.0 kernel.

With the BeagleBone capable of being a USB pass through device, the next challenge was sending keypresses to another USB device. For this, a Teensy 2.0 was connected to the UART of the BeagleBone. According to [pmf], this is one of the few examples of the Teensy serving as a composite USB device – sending both keyboard and mouse info.

There are a few neat features for [pmf]’s build: the keyboard and mouse don’t disconnect when switching, and thanks to a slight modification of the USB OTG adapter, this will also charge a phone as well as allow for the use of a keyboard. Because the BeagleBone Black has more than one UART this build can also switch keyboards and mice between more than two computers. For those of us who invest heavily in keyboards, it’s a godsend.

Hackaday Prize Entry: A Better KVM Switch

May 5, 2015 by Brian Benchoff 60 Comments

Now it’s not uncommon to have a desktop and a laptop at a battlestation with tablets waiting in the wings. Add in a few Raspis, consoles, and various cheap computers, and it’s pretty easy to have an enormous number of machines and monitors on a desk. Traditionally, a KVM switch would be the solution to this, sharing a keyboard, mouse, and monitor with many different boxes, but this is an ugly solution. [frankstripod] has a device that fixes that with some interesting software and a few USB hacks.

[frankstripod] is in love with a program called Synergy this program combines the keyboard, mouse, and display of several computers over a network so you’ll only ever have to use one keyboard and mouse; it’s as simple as dragging your mouse from one computer to the other. There are a few limitations, though: keyboards don’t work until the OS has loaded (no BIOS access, then), it doesn’t work if the network is down, and setup can be complicated. This project aims to replace the ‘server’ part of a Synergy setup with a small, networkable KVM.

Right now the plan is to use a small embedded board running Linux to read a USB keyboard and switch the output between several computers. A few scripts detect the mouse moving from one screen to another, and a microcontroller switches USB output between each computer. If it sounds weird, you’re right, but it does work: [frank]’s 2014 Hackaday Prize project was a mouse that worked with two computers at once.