Modded Microwave Sets Its Own Clock

Of all the appliances in your house, perhaps the most annoying is a microwave with a flashing unset clock. Even though a lot of devices auto-set their time these days, most appliances need to have their time set after being unplugged or after a power outage. [Tiago] switches off power to some of his appliances while he’s at work to save a bit of power, and every time he plugs his microwave back in he has to manually reset the clock.

Thankfully [Tiago] wrote in with his solution to this problem: an add-on to his microwave that automatically sets the time over the network. [Tiago]’s project uses an ESP8266 running the Lua-based firmware we’ve featured before. The ESP module connects to [Tiago]’s WiFi network and pulls the current time off of his Linux server.

Next, [Tiago] ripped apart his microwave and tacked some wires on the “set time” button and on the two output pins of the microwave’s rotary encoder. He ran all three signals through optoisolators for safety, and then routed them to a few GPIO pins on his ESP module. When the microwave and the ESP module are powered up, [Tiago]’s Lua script pulls the time from his server, simulates a press of the “set time” button, and simulates the rotary encoder output to set the microwave’s time.

While [Tiago] didn’t post any detailed information on his build, it looks like a great idea that could easily be improved on (like adding NTP support). Check out the video after the break to see the setup in action.

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CastAR Teardown

A little more than a year ago, castAR, the augmented reality glasses with projectors and retro-reflective surfaces made it to Kickstarter. Since then we’ve seen it at Maker Faire, seen it used for visualizing 3D prints, and sat down with the latest version of the hardware. Now, one of the two people we trust to do a proper teardown finally got his developer version of the castAR.

Before [Mike] digs into the hardware, a quick refresher of how the castAR works: inside the glasses are two 720p projectors that shine an image on a piece of retroreflective fabric. This image reflects directly back to the glasses, where a pair of polarized glasses (like the kind you’ll find from a 3D TV), separate the image into left and right for each eye. Add some head tracking capabilities to the glasses, and you have a castAR.

The glasses come with a small bodypack that powers the glasses, adds two jacks for the accessory sockets, and switches the HDMI signal coming from the computer. The glasses are where the real fun starts with two cameras, two projectors, and a few very big chips. The projector itself is a huge innovation; [Jeri] is on record as saying the lens manufacturers told her the optical setup shouldn’t work.

As far as chips go, there’s an HDMI receiver and an Altera Cyclone FPGA. There’s also a neat little graphic from Asteroids on the board. Video below.

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Tube Map Radio and Denki Puzzles

Sometimes, awesomeness passes us by and we don’t notice it until a while later. This is from 2012, but it’s so friggin’ insane we just have to cover it even if it’s late. Yuri Suzuki is an installation artist who designed the Tube Map Radio and Denki Puzzles.

The Tube Map Radio is inspired by a diagram created by the original designer of the London Tube map, Harry Beck, which shows the lines and stations of the London Underground rail network as an annotated electrical circuit. Iconic landmarks on this map are represented by components relating to their functions, including a speaker where Speaker’s Corner sits, battery representing Battersea Power Station and Piccadilly Circus marked as Piccadilly Circuit. The work was commissioned by the Design Museum London, and the PCB layout was done by Masahiko Shindo (Shindo Denki Sekkei). The idea was to bring the electronics out of the “black box” and not just display it, but to have it laid out in a fashion that people could try to understand how it really works.

The other project called Denki Puzzles is equally remarkable. It’s a kit meant to teach electronics, using a set of snap-fit components. But instead of having all “bricks” or units of the same shape, the Denki Puzzles are a collection of printed circuit board pieces whose form indicate a particular function. Fit the pieces together as a sort of physical circuit diagram and you’ll be able to build working electronics. For example, the LED unit looks like a 8 pointed star, and the resistance unit looks like a resistance symbol. Check out some pictures and a video after the break

Photo’s Credit : Hitomi Kai Yoda.

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Meet The Machines That Build Complex PCBs

You can etch a simple PCB at home with a few chemicals and some patience. However, once you get to multilayer boards, you’re going to want to pay someone to do the dirty work.

The folks behind the USB Armory project visited the factories that build their 6 layer PCB and assemble their final product. Then they posted a full walkthrough of the machines used in the manufacturing process.

The boards start out as layers of copper laminates. Each one is etched by applying a film, using a laser to print the design from a Gerber file, and etching away the unwanted copper in a solution. Then the copper and fibreglass prepreg sandwich is bonded together with epoxy and a big press.

Bonded boards then get drilled for vias, run through plating and solder mask processes and finally plated using an Electroless Nickel Immersion Gold (ENIG) process to give them that shiny gold finish. These completed boards are shipped off to another company, where a pick and place followed by reflow soldering mounts all the components to the board. An X-Ray is used to verify that the BGA parts are soldered correctly.

The walkthrough gives a detailed explanation of the process. It shows us the machines that create products we rely on daily, but never get to see.

Using I2C Addresses as Chip Selects

I2C has a seven-bit address space, and you’re thinking “when do I ever need more than 127 devices on a pair of wires?” So you order up some parts only to find that they have one, two, or three user-configurable address pins for any given device type. And you need a bunch more than four or eight capacitive sensor buttons on your project. What do you do?

If you’re reader [Marv G], you think outside the box and realize that you can change the addresses on the fly by toggling address pins high and low with your microcontroller. That is, you can use a single I2C address pin for each device as a chip select signal just like you would have with SPI.

That’s it, really. [Marv G] goes through all of the other possible options in his writeup, and they’re all unsavory: multiple I2C busses, a multiplexer, buying different sensors, or changing micros. None of these are as straightforward as just running some more wires and toggling these with your micro.

We’d even go so far as to suggest that you could fan these chip select lines out with a shift register or one of those 1-of-N decoder chips, depending on how many I2C devices you need to chip-selectify. (We’re thinking 74HC595 or 74HC154.)

Along the way, we found this nice list of the number of address pins for a bunch of common peripherals provided by [LadyAda], in case you don’t believe us about how ubiquitous this problem is. How many devices on that list have one (1!!) address pin?

At the end of his post, [Marv G] asks if anyone else has thought of this chip select trick before. We hadn’t. Here’s your chance to play the smart-ass in the comments.

Build a Precision Voltage Reference Box

So you just scored a vintage piece of test gear, or maybe you just bought a fancy new DMM (Hmm…We love that new multimeter smell!) But can it read voltage accurately? How can you be sure? Well, that’s why you should build yourself a voltage reference box.

Youtuber [Scullcom’s] latest video has you covered. Wants some specs? Sure. How does a precision 10v and 5v output with only ±0.025% and an amazing 2.5ppm/°C sound? That’s very impress for something you can cobble together yourself.  We find it interesting that he actually uses some ebay parts to pull off this build. The LiPo battery, USB LiPo charging circuit, and boost regulator are all sourced from ebay. Not to worry though, as these parts are only used to supply power to a 15 volt linear regulator. The real magic happens in the Texas Instruments REF102 precision voltage reference. You give it a decently clean 12-36 volts, and it will give you a 10 volt reference out.  These amazing chips are able to obtain such precision in part because they are calibrated (or more specifically “laser trimmed”) from the factory. A secondary output of 5 volt is achieved by using a differential amplifier.

Warning: The video after the break is a bit on the long side(43 mins), so you might want to make some popcorn. But we find [Scullcom’s] teaching style to be lovely, and he does a wonderful job of explaining the project start to finish, soup to nuts. Continue reading “Build a Precision Voltage Reference Box”

The Oldland CPU 32-bit FPGA Core

Field Programmable Gate Arrays (FPGAs) let you program any logic you’d like onto a chip. You write your logic using a hardware description language, then flash it to the FPGA. You can even design your own processor and flash it to the chip.

That’s exactly what [jamieiles] has done with the Oldland CPU. It’s an open source 32 bit CPU core that you can synthesize for use on an FPGA. Not only can you browse through all the Verilog code in the Github repo, but there’s also a bunch of tools for working with this CPU core.

Included with the package is oldland-rtlsim, which lets you simulate the processor on a PC. The oldland-debug tool lets you connect to the processor for programming and debugging over JTAG. Finally, there’s a GNU toolchain port that lets you build C code for the device.

Going one step futher, [jamieiles] built a full SoC around the Oldland core. This has SPI, UART, timers, and more features you’d expect to find in a microcontroller. It can be flashed to the relatively cheap Terasic DE0-Nano board.

[jamieiles] has also ported u-boot to the processor, and the next thing on the list is the Linux kernel. If you’ve ever been interested in how CPUs actually work, this is a neat project to look through. If you want more open source CPU cores, check out OpenCores.