Hackaday Prize Entry: A PC-XT Clone Powered By AVR

May 21, 2017 by 19 Comments

There is a high probability that the device on which you are reading this comes somehow loosely under the broad definition of a PC. The familiar x86 architecture with peripheral standards has trounced all its competitors over the years, to the extent that it is only in the mobile and tablet space of personal computing that it has not become dominant.

The modern PC with its multi-core processor and 64-bit instruction set is a world away from its 16-bit ancestor from the early 1980s. Those early PCs were computers in the manner of the day, in which there were relatively few peripherals, and the microprocessor bus was exposed almost directly rather than through the abstractions and gatekeepers we’d expect to see today. The 8088 processor with an 8-bit external bus though is the primordial PC processor, and within reason you will find software written for DOS on those earliest IBM machines will often still run on your multiprocessor behemoth over a DOS-like layer on your present-day operating system. This 35-year-plus chain of mostly unbroken compatibility is both a remarkable feat of engineering and a millstone round the necks of modern PC hardware and OS developers.

Those early PCs have captured the attention of [esot.eric], who has come up with the interesting project of interfacing an AVR microcontroller to the 8088 system bus of one of those early PCs. Thus all those PC peripherals could be made to run under the control of something a little more up-to-date. When you consider that the 8088 ran at a modest 300KIPS and that the AVR is capable of running at a by comparison blisteringly fast 22MIPS, the idea was that it should be able to emulate an 8088 at the same speed as an original, if not faster. His progress makes for a long and fascinating read, so far he has accessed the PC’s 640KB of RAM reliably, talked to an ISA-bus parallel port, and made a CGA card produce colours and characters. Interestingly the AVR has the potential for speed enhancements not possible with an 8088, for example it can use its own internal UART with many fewer instructions than it would use to access the PC UART, and its internal Flash memory can contain the PC BIOS and read it a huge amount faster than a real BIOS ROM could be on real PC hardware.

In case you were wondering what use an 8088 PC could be put to, take a look at this impressive demo. Don’t have one yourself? Build one.

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DIY USB Power Bank

May 21, 2017 by 47 Comments

USB power banks give your phone some extra juice on the go. You can find them in all shapes and sizes from various retailers, but why not build your own?

[Kim] has a walkthrough on how to do just that. This DIY USB Power Bank packs 18650 battery cells and a power management board into a 3D printed case. The four cells provide 16,000 mAh, which should give you a few charges. The end product looks pretty good, and comes in a bit cheaper than buying a power bank of similar capacity.

The power management hardware being used here appears to be a generic part used in many power bank designs. It performs the necessary voltage conversions and manages charge and discharge to avoid damaging the cells. A small display shows the state of the battery pack.

You might prefer to buy a power bank off the shelf, but this design could be perfect solution for adding batteries to other projects. With a few cells and this management board, you have a stable 5 V output with USB charging. The 2.1 A output should be enough to power most boards, including Raspberry Pis. While we’ve seen other DIY Raspberry Pi power banks in the past, this board gets the job done for $3.

 

Humans May Have Accidentally Created A Radiation Shield Around Earth

May 21, 2017 by 60 Comments

 

NASA spends a lot of time researching the Earth and its surrounding space environment. One particular feature of interest are the Van Allen belts, so much so that NASA built special probes to study them! They’ve now discovered a protective bubble they believe has been generated by human transmissions in the VLF range.

VLF transmissions cover the 3-30 kHz range, and thus bandwidth is highly limited. VLF hardware is primarily used to communicate with submarines, often to remind them that, yes, everything is still fine and there’s no need to launch the nukes yet.  It’s also used for navigation and broadcasting time signals.

It seems that this human transmission has created a barrier of sorts in the atmosphere that protects it against radiation from space. Interestingly, the outward edge of this “VLF Bubble” seems to correspond very closely with the innermost edge of the Van Allen belts caused by Earth’s magnetic field. What’s more, the inner limit of the Van Allan belts now appears to be much farther away from the Earth’s surface than it was in the 1960s, which suggests that man-made VLF transmissions could be responsible for pushing the boundary outwards.

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Wake Up To Fresh Coffee!

May 21, 2017 by 18 Comments

Be careful what you say when you are shown a commercial product that you think you could make yourself, you might find yourself having to make good on your promise.

When he was shown a crowdfunded alarm clock coffee maker, [Fabien-Chouteau] said “just give me an espresso machine and I can do the same”. A Nespresso capsule coffee machine duly appeared on his bench, so it was time to make good on the promise.

The operation of a Nespresso machine is simple enough, there is a big lever on the front that opens the capsule slot and allows a spent capsule to drop into a hopper. Drop in a new capsule, pull the lever down to load it into the mechanism, then press one of the buttons to tell it to prime itself. After a minute you can them press either of the large cup or the small cup buttons, and your coffee will be delivered.

To automate this with an alarm clock there is no necessity to operate the lever, it’s safe to leave loading a capsule to the user. Therefore all the clock has to do is trigger the process by operating the buttons. A quick investigation with a multimeter on the button PCB found that the voltage present was 15 V, well above the logic level of the STM32F469 board slated for the clock. Thus a simple circuit was devised using a MOSFET to  do the switching.

Finally, the clock software was created for the STM32F469. The chip’s 2D graphics acceleration hardware and the development board’s high quality display make for a very slick interface indeed.

You can see the resulting clock in the video below the break. It’s an alarm clock coffeemaker we’d be proud to have beside our beds, but there’s one slight worry. On a mains-powered device like the Nespresso the low voltage rails are not always mains-isolated, and it’s not clear whether or not this is the case. Maybe we’d have incorporated an opto-isolator, just in case.

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Multipurpose ESP8266 Keychain

May 21, 2017 by 30 Comments

One of the best feature of the ESP8266 is its ability to self-host a web server, allowing for fairly complicated user interactions. The dEEbugger by [S-March] is a nifty little ESP8266 based device with a plethora of features in a small package.

The USB-powered device has a web user interface that enables it to be used as a low-bandwidth oscilloscope, I2C terminal, or UART terminal. As a scope, you may connect to it via your tablet and then use it as a remote voltage monitor. There is a peak detection feature which is a nice touch and gives the entire project a premium feel.

The serial terminal on an ESP8266 is not something new yet it is helpful in disconnecting the console window from the bench. The I2C terminal is where the device really shines as it can scan for connected devices on the connected bus. This Bus-Pirate like feature is useful for beginners as the software can scan the registers addresses of the devices as well.

[S-March] has made the schematic in PDF format as well as the entire code for the project available on GitHub so go right ahead and make it your own. We have had an ESP8266 based VT Terminal device in the past and merging the two would make for an excellent maker tool.

Thanks for the tip [René Arts]

Dis-Integrated 6502 Running Programs; Acting Like Computer

May 20, 2017 by 31 Comments

[Eric Schlaepfer] tends to turn up to Maker Faire with projects you simply don’t want to miss. This year is no different. Twelve months ago we delighted in seeing his 6502 processor built from an enormous reel of discrete MOSFETs. At the time it was freshly built and running random code to happily blink the LEDs reflecting activity in the registers. This year he’s given that blinking meaning and is running real programs on his Monster 6502 processor.

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The Tiniest Mechanical Keyboard Ever

May 20, 2017 by 34 Comments

Owning a mechanical keyboard makes you a better person. It puts you above everyone else. Of course, owning a mechanical keyboard does come with some downsides. Carrying a mechanical keyboard around all the time to tell everyone else you’re better than them is usually impractical, but [cahbtexhuk Joric] has come up with a solution. It’s a miniature Bluetooth mechanical keyboard that’s also a keychain.

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