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Faster Benchmarks With Slower Hardware

hardware

The Bus Pirate is a cheap, simple, Swiss army knife of electronic prototyping, capable of programming FPGAs, and writing to Flash memory. The uISP is possibly the most minimal way of programming Atmel chips over USB, using less than $5 in components. Although the uISP is using a slower chip and bit-banging the USB protocol, it turns out it’s actually faster when operating as a programmer for SPI Flash memories.

Most of [Necromancer]‘s work involves flashing routers and the like, and he found the Bus Pirate was far too slow for his liking – he was spending the better part of four minutes to write a 2 MiB SPI Flash. Figuring he couldn’t do much worse, he wrote two firmwares for the uISP to put some data on a Flash chip, one a serial programmer, the other a much more optimized version.

Although the ATMega in the uISP is running at about half the speed as the PIC in the Bus Pirate, [Necromancer] found the optimized firmware takes nearly half the time to write to an 8 MiB Flash chip than the Bus Pirate.

It’s an impressive accomplishment, considering the Bus Pirate has a dedicated USB to serial chip, the uISP is bitbanging its USB connection, and the BP is running with a much faster clock. [Necro] thinks the problem with the Bus Pirate is the fact the bandwidth is capped to 115200 bps, or a maximum throughput of 14 kiB/s. Getting rid of this handicap and optimizing the delay loop makes the cheaper device faster.

Video: The Lowly Diode — Umpteen Functions with Only Two Pins

 

The lowly diode, a device with only two leads, can nonetheless do many things. Diodes can detect, rectify, suppress, emit light, detect light, change capacitance, emit microwaves and more. This wide range of use means diodes are included in almost every design and it’s well worth learning more about the inner workings of all kinds of diodes.

My introduction to diodes started like many of my generation with a homemade crystal radio set. My first diode was a piece of pencil graphite in contact with an old fashion safety razor with the joint of the two dissimilar materials — graphite and steel — creating the diode. In this configuration the diode is said to be “detecting” which is the act of turning a weak radio signal into a weak audio signal. At least in my home town of Marion Indiana, one radio station was stronger than the other so that I didn’t have to listen to two stations at once.

Germanium Glass Diode

The venerable 1N34A Germanium Signal Diode.

I eventually learned about “real” diodes and the 1N34A Germanium diode was my “goto” diode into my teens. Nowadays looking into a modern version of the 1N34A you can still see the semblance of the old “cat’s whisker” by looking carefully into the diode.

A quick and somewhat inaccurate semblance of the way a diode works can be demonstrated with marbles and jacks representing negative electrons and positive “holes”. Holes are basically an atom missing an electron due to the combination of elements, a process known as doping. Join me after the break for the explanation.

Demonstrating a PN Junction with marbles and Jacks.

Demonstrating a PN Junction with marbles and Jacks.

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[Afrotech]‘s Guide To Class D Amplifiers

classd

Hang around in any of the many guitar or audiophile forums or discussion boards for long enough, and eventually you’ll come across the arguments over amplifier topologies. One of the more interesting and useful of these classes of amplifier is class d – they’re extremely efficient and when well designed can sound pretty good. [Afrotech] is here to show you how they work, and how to build a 15 Watt amp using a $3 class d amplifier chip.

The very definition of an amplifier is taking a low power signal and transforming it into a high power signal. A great way to modulate a high power signal very quickly is by modulating a square wave with pulse width modulation. A class d amplifier takes a low power input signal, uses it to modulate the duty cycle of a high power square wave, and with a little filtering, amplifies the low power input.

To demo this, [Afrotech] used TI’s TPA3122 class d amplifier chip. It’s a pretty cheap chip for being a 15 Watt stereo amplifier, and the circuit is simple enough to build on a breadboard. With a few caps, resistors, and a pair of inductors, [Afrotech] built this one-chip amplifier that’s capable of powering some pretty big speakers. It’s also very efficient – no heat sink required.

Although class d amps are extremely efficient. there are a few people out there that say because the amplifier is basically a filtered square wave, you’ll be able to hear a difference in the audio over class a or class ab amplifiers. This led to the development of class t amplifiers, basically a class d amp with a higher switching speed (Megahertz for class t, a few hundred kilohertz for class d). Still, if you need a cheap amplifier for a DIY boombox or any other high power application, you could do a lot worse than a simple class d amp.

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Converting The Wacom Intuos Into A Cintiq

wacom

Wacom, purveyors of fine pen tablets for digital artists, basically have two product lines of pen tablets. The first, Intuos, is a great pen tablet that give an artist the ability to turn a computer into a virtual dead tree notebook. The second product line, the Cintiq, takes the same technology and adds an LCD to the mix, effectively turning a drawing tablet into a second display. [Bumhee] wanted a Cintiq, but didn’t want to pay the Cintiq price, leading him to install a display in his old Intuos tablet. It’s an amazingly simple build, making us think we’ll be seeing a few derivatives of his work in the future.

The display [Bumhee] used for this modification is a Retina display from an iPad. With the right adapter, you can easily connect one of these displays to a computer, giving you a very thin 2048×1536 9.7″ display. The initial tests to see if this mod would work on his tablet – removing the metal shield on the display, placing it on the tablet, and drawing – were a success, giving [Bumhee] the confidence to irreparably modify his tablet.

From there, the modification was a simple matter of cutting up the enclosure of the tablet, installing the display with a few screws, and installing a piece of glass over the display. Very easy, and it’s just about the only way you’re going to get a pen tablet with a small, high-resolution display for less than a thousand dollars.

Thanks [David] for sending this one in.

The Development Of A Hardware Random Number Generator

rng

[Ian] had a need for a lot of random numbers. There are dozens of commercial offerings when it comes to RNGs, but there are also hundreds of different ways for an electronics hobbyist to shoot random bits at a serial port. One of these methods is an RNG based on the avalanche breakdown noise in a PN junction. As with any circuit in hobbyist electronics, there are dozens of prototypes floating out there on the web, but not too many finished projects. [Ian] decided he would build one of these RNGs as a prototype and bring it to something resembling a finished project.

An avalanche noise RNG takes advantage of the fact that a strongly reverse-biased PN junction, like one found in a transistor, will create a condition where one electron knocks another electron out of place, leading to a sustained chain reaction. It’s quantum, it’s chaotic, it makes for a great source for a random number generator, and there are already dozens of prototype circuits around the Internet.

[Ian] took one of these circuit designs by [Will Ware] and started the iterations that would lead to a finished design. Round one was a simple PCB with the basic circuit and a power supply. Just a few transistors, resistors, and a DC/DC boost converter. Confirming the circuit was generating noise, the next iteration brought in an ADC and an ARM micro with a USB interface. Iterating over this again with an improved ADC – 20 megasamples per second – the design finally reached a point where a final PCB could be designed.

In the end, [Ian] turned a simple circuit that could have been built on a breadboard into a USB device that throws 9kB/s of random data into a computer. The data are actually good, too: the project passed most of the Dieharder test suite, making it very useful for whatever crypto or gaming application [Ian] has in mind.

Developed on Hackaday: We Have Final Prototypes!

Mooltipass final prototype

The last few weeks have been quite tense for the Mooltipass team as we were impatiently waiting for our smart cards, cases and front panels to come back from production. Today we received a package from China, so we knew it was the hour of truth. Follow us after the break if you have a good internet connection and want to see more pictures of the final product

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Developed on Hackaday: Front Panels and Beta Testers Program

mooltipass front panel

We’re pretty sure that most of our readers already know it by now, but we’ll tell you anyway: the Hackaday community (writers and readers) is currently developing an offline password keeper, the Mooltipass. As it has been more than two weeks since we wrote an article about our progress, today’s will be about the Mooltipass front panels and our beta testers program.

At the end of our mechanical design rundown article we showed that we were originally planning to put a slightly tinted acrylic panel on top of our device. We however could still make out the Mooltipass’ insides, which wasn’t in line with the nice professional look we wanted. We then designed another front panel, one which was transparent above the OLED screen/LEDs and opaque (black) on top of the rest. To our surprise the result still wasn’t as good as we had hoped, as the contrast between the front panel and the screens/LEDs was too big. We finally came up with the panel shown above (see GitHub repository folder) which combines the two techniques previously described. As it is still in China, we’ll show you the final result when we get it in our hands.

We launched around 10 case prototypes in production, they will soon be shipped to our current contributors/advisers together with the smart cards chosen by Hackaday readers. In the meantime we sent our official call for beta testers to our mailing list recipients and hackaday.io followers, in which we asked them to fill a small form that will allow us to know them a bit better. We asked about their home/work computer setup, their level of expertise, their willingness to contribute to the prototype cost and finally specifics about who would use the Mooltipass they’d receive. We are targeting a broad range of users but also testers that will provide us with detailed feedback and clear bug reports.

We also spent quite a while searching for cheaper alternate parts that could be sourced in relatively big quantities. This is usually an overlooked aspect of a project so we preferred to tackle this as soon as possible. In a few weeks the contributors and I will receive all the components required to assemble our final prototype (front panels / case / top & bottom PCBs / smart cards) and it will be time to write a new update. Want to stay informed? You can join the official Mooltipass Google Group or follow us on Hackaday Projects.