Flip The Switch On This I2C Controlled USB Hub

September 11, 2023 by Tom Nardi 13 Comments

You’ve probably seen USB hubs with physical switches for each port, they provide a handy way to cut the power to individual devices, but only if you’re close enough to flip them. They won’t do you much good if you want to pull the plug on a USB gadget remotely.

That’s why [Jim Heaney] created the I2C-USB-Hub. The device takes your standard USB 2.0 hub circuit, and adds in a MT9700 P-MOSFET load switch for each port. The enable pin on each of these switches is in turn connected to one of the output pins of a PCA9557PW I2C I/O chip. That means controlling each port is as easy as sending the proper sequence of bits over the wire, though [Jim] says he does plan on writing up an Arduino library to make flipping the digital switches a little more user friendly.

Since the 8-bit chip had a few extra pins left over, [Jim] wired one up to serve as a master control for the LED indicator lights on the PCB. Another is used to adjust the current limit on the MT9700 between 500 mA and 1 A.

While naturally we’re big fans of spinning up your own hardware here at Hackaday, we’ve also seen similar results achieved by modifying an off-the-shelf USB hub.

The Augmented Reality Breadboard Of The Future

May 27, 2019 by Tom Nardi 15 Comments

You’d be hard pressed to find a carpenter who didn’t own a hammer, or a painter that didn’t have a couple of brushes kicking around. Some tools are simply so fundamental to their respective craft that their ownership is essentially a given. The same could be said of the breadboard: if you’re working with electronics on the hobby or even professional level, you’ve certainly spent a decent amount of time poking components and wires into one of these quintessential prototyping tools.

There’s little danger that the breadboard will loose its relevance going forward, but if [Andrea Bianchi] and her team have anything to say about it, it might learn some impressive new tricks. Developed at the Korean Advanced Institute of Science and Technology, VirtualComponent uses augmented reality and some very clever electronics to transform the classic breadboard into a powerful mixed-reality tool for testing and simulating circuits. It’s not going to replace the $3 breadboard you’ve got hiding at the bottom of your tool bag, but one day it might be standard equipment in electronics classrooms.

The short version is that VirtualComponent is essentially a dynamic breadboard. Holes in the same row are still electrically linked like in the classic breadboard, but with two AD75019 cross-point switch arrays and an Arduino in the base, it has the ability to virtually “plug in” components at arbitrary locations as selected by the user. So rather than having to physically insert a resistor, the user can simply tell the software to connect a resistor between two selected holes and the cross-point array will do the rest.

What’s more, many of those components can be either simulated or at least augmented in software. For example, by using AD5241 digital potentiometers, VirtualComponent can adjust the value of the virtual resistor. To provide variable capacitance, a similar trick can be pulled off using an array of real capacitors and a ADG715 digital switch to connect them together; essentially automating what the classic “Decade Box” does. In the demonstration video after the break, this capability is extended all the way out to connecting a virtual function generator to the circuit.

The whole system is controlled by way of an Android tablet suspended over the breadboard. Using the tablet’s camera, the software provides an augmented reality view of both the physical and virtual components of the circuit. With a few taps the user can add or edit their virtual hardware and immediately see how it changes the behavior of the physical circuit on the bench.

People have been trying to improve the breadboard for years, but so far it seems like nothing has really stuck around. Given how complex VirtualComponent is, they’ll likely have an even harder time gaining traction. That said, we can’t help but be excited about the potential augmented reality has for hardware development.

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The Network Of 1-Wire Devices

October 18, 2014 by Brian Benchoff 13 Comments

teensynet

[jimmayhugh] is a homebrewer and has multiple fermentation chambers and storage coolers scattered around his home. Lucky him. Nevertheless, multiple ways of making and storing beer requires some way to tell the temperature of his coolers and fermenters. There aren’t many temperature controllers that will monitor more than two digital thermometers or thermocouples, so he came up with his own. It’s called TeensyNet, and it’s able to monitor and control up to 36 1-wire devices and ties everything into his home network.

Everything in this system uses the 1-Wire protocol, a bus designed by Dallas Semiconductor that can connect devices with only two wires; data and ground. (To be a fly on the wall during that marketing meeting…) [jimmay] is using temperature sensors, digital switches, thermocouples, and even a graphic LCD with his 1-wire system, with everything controlled by a Teensy 3.1 and Ethernet module to push everything up to his network.

With everything connected to the network, [jimmay] can get on his personal TeensyNet webpage and check out the status of all the devices connected to any of his network controllers. This is something the engineers at Dallas probably never dreamed of, and it’s an interesting look at what the future of Home Automation will be, if not for a network connected relay.