Component Survey

Some components are found in every design, others are more rare. I’ve met designers claiming that digital constructions not including a PIC must be broken or trivial enough to implement using a single PIC. Still, there are some unique components out there.

For the engineer striving for a truly symmetric world, the WOM is a must. Signetics and National helps us there. For the apocalyptic individuals among us, Maxwell’s Nuclear Event Detector might be of interest. Connect it to trigger the closing mechanism of your bunker and you can sleep tight.

Still, the WOM comes with the most useful figure I’ve encountered yet (thanks to Reine for the tip): number of pins remaining / number of socket insertions.

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PLA and Temperatures

The eMaker Huxley 3D printer comes with a roll of while PLA from Faberdashery. A material that is new to me (I’ve only printed ABS before). PLA operates at a cooler temperature, but it requires a phase change (from solid to floating), thus requiring quite a lot of energy when in the nozzle.

Temperature wise, the nozzle can be set to 190 degrees Celsius. This provides a steady flow and prevents the nozzle from clogging. The illusive bed temperature seems to hide between 65 and 85 dgC. The issue is that the temperature sensor not is placed on the surface of the bed, so the bed needs to be held at a given temperature for a while to let it stabilize. This is well worth considering if you experience good builds at first, then a first layer that has a tendency to peel off.

Right now, I’m aiming at finding a temperature that prevents the bottom layer from peeing of and losing shape due to being too cold. At the same time, I’m trying to configure the cool settings to prevent the hot nozzle from causing small layers to lose shape due to overheat. Notice the tip of the calibration pyramid in the photo in this article (yes, the extruder needs some more calibration love).

Still, even though the calibration seems to take some time, the progress is nice. Thanks to some filing and gentle force, a stand for a heavy duty filament spool holder is taking shape.

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Extruder Issues

I thought that I ran into an extruder issue yesterday evening. The filament simply got stuck. However, looking at the filament shown in the picture, you can see that the plastic thickens just before (to the left of) the spot where it got stuck and the extruder has eaten into it.

The issue was easily resolved by backing the filament, but the print in question was lost. This highlights the need of a sensor ensuring that the filament actually is moving. Perhaps something that can be constructed from an old mechanical mouse. Had I left the printer alone, it would had eaten its way through the filament, making the operation of backing the filament out of the extrusion head slightly more challenging.

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Adafruit at the Arduino Factory

Adafruit, a great site with projects, forums, a blog and a shop, when to Italy an visited the Arduino factory. They made a video of their trip shown below.

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SOPA

Today, there will not be an in-depth article. Instead, I urge you to read up on SOPA/PIPA and make your voice heard.

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EMaker Huxley Wiring

I’ve finally found the time to wire up my EMaker Huxley 3D printer. Let me summarize the experience – trust the images, not the words, sometimes. At other times, the instructions explicitly states that the image is wrong.

Generally, the instructions work well, but certain aspects, such as how to wire up the actual power connector, the orientation of motor connectors and such are lacking. I really did expect a kit build to come with the axes moving in the correctly direction out of the box. Still, only the extruder and Z-axis needed re-orienting. A word of caution – having the X, Y or Z axis moving in the wrong direction means that pressing the home button is a bad idea. Still, manually clicking the end stop prevents any damage.

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Lost Knowledge

Past computers did not come with quick start sheets or awkwardly worded manuals that barely scratched the surface of the product. They came with programming manuals, listings of memory maps, I/O registers, schematics and everything else the tinkering engineer might rely on.

The PageTable site contains a literature category, holding many gems. Some of historical interest, others of a more nostalgic nature (German). Now I just need to locate my old PDP manuals and contribute!

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Machine Code History

PageTable covers computing at the deepest possible level, without turning to physics. The site covers topics such as quirks of the first ever CPU, the Intel 4004, copying disks on the C64quickly, using branch delay slots, and much, much more. The topics in themselves can be entertaining, as historical and nostalgic curiosities. However, the depth of the analysis turns them into lectures into how to do thing efficiently.

On a 1MHz CPU, wasting 10000 cycles per second means performance degradation. This eats 1% out of the complete performance of the system. On a multi-giga-Hertz system, with out-of-order execution and a super-scalar execution engine, not so much. Still, taking the extra time to optimize loops, calculating things intelligently, and not always rely on a dynamic list and for-loops can make a big difference.

For a more modern context, here and here is a list of instruction set manuals and ABI (Application Binary Interface, i.e. calling conventions, et cetera) collected by Thiago Macieria. This list covers IA-32, x86-64, IA-64, ARM (32 and 64 bits), MIPS (32 and 64 bits), POWER and SPARC. Not only do these documents carry loads on interesting information, they also serve as a reminder that even the very top notch systems of today, rely on the same basic mechanisms as their oldest and smallest relatives.

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Forums and Sites

As a part in our efforts to be a good source of information, we would like to introduce our resources page. Here, we will gather a set of electronic sites that can be useful for you.

When browsing the resources, do not miss our GCC Error Message list – one of the few that comes complete with a set of solutions.

If you have a site that you feel would be a good addition, please contact e8johan -at- gmail. If you want to read the motivation behind the first list of sites, continue reading below.

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AVR Assembler

Programming in assembler is one of the key skills that I believe all engineers should acquire. It is not very important which architecture, only that one understands the basic language spoken by computers (machine code and assembler usually have a 1:1 mapping). This teaches you about the limitations of a machine, what takes effort and what is easy, what eats memory and what can be handled using a single accumulator. To put it in a single sentence – knowing assembler, you know how a computer works.

One architecture that is nice to learn is the AVRs. The PIC teaches you more about the quirks of a RISC CPU, the AVR teaches you more about proper assembler. RetroDan provides the great text A Moron’s Guide to Starting in AVR Assembler. It introduces the AVR and its assembler language. It also covers useful tidbits such as SPI, timers, counters, PWM, ADC, et cetera.

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