μblog: engineering from the trenches

I have made the first step in getting an entry into the TI msp430 design contest: getting the LED to blink. The msp430 development kit comes with a JTAG flash emulation tool, a small dev board with a 64 pin ZIF socket as well as IAR workbench kickstart software. Running the IAR workbench is pretty easy so I opened their LED blink example and was able to compile it and then put the device into debug mode to download the binary onto the device and provide a clock via JTAG. After doing this, I verified that everything worked fine by unplugging the JTAG tool, hooking up XIN, XOUT, DVcc, DVss and \RST to a breadboard and a benchtop powersupply. When I applied power, the LED started blinking and I could see it blinking all the way down to about 1.5V (below the 1.8V spec for this MSP430F149.) Throwing in the JTAG tool/IAR workbench manual at the bottom.

( slau138c.pdf )

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I recently found out that Penn State University decided to pony up the cash to allow all students/faculty/staff full access to all of the music on Napster. It looks like Napster works with whatever devices support the PlayForSure scheme from Microsoft. This protocol makes sure that the device honors the WMA DRM that is supposed to protect the file from illegal piracy, although, Napster has no problems burning WMA files you download to CD. One of the large mp3 player manufacturers that does not subscribe to this program is Apple, so is all hope lost? The program FairUse4WM is able to extract the keys locally stored in your Windows Media Player and then strip the DRM protection leaving a plain WMA file, that is, if you can play the protected file on your PC, then you can remove the protection. You can then add the plain WMA file to your iTunes library and have it converted to AAC and then simply transfer the file on your iPod and enjoy.

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Texas Instuments is sponsoring another design contest with the msp430 architecture. There is a downloadable development tool for the msp430 as well as an available online simulator so if you have a creative project, you need not actually invest money in a development kit, not that it’s expensive ($15.) Two finalists get some HDTVs and trips to the forthcoming msp430 conference.

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This low frequency (0.02Hz-25KHz) spectrum analyzer just arrived today, probably both older and more intelligent (features 4 LSI filter chips) than myself. After setting it up, I had quite a hard time locating the manuals for this device online and had to resort to finding the CD that the vendor shipped with the device. After much contemplation, I think I might become the only online-source for the HP 3582A operating manuals.

( HP-3582A-Manual.pdf ) [15MB]

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Day #2 of neural interfaces workshop is done. You probably can’t see it, but Nathalia Peixoto is giving a short (5 minute/3 slide) presentation in the image to show off CNE/NDL/her own work. Sridhar and I presented a poster (4MB) which Sridhar Sunderam is mostly responsible for creating. There was a lot of good information which boils down to this:

(1) we need more flexible electrodes with smaller footprints (microwire/silicon with holes) to limit immune response to implantation.

(2) we need to allow the electrodes to “float” with the brain versus the skull with flexible conductors to minimize damage

(3) silicon electrodes with on-board amps and inductive-coil based power are still a dream

(4) chronic (18+ month) recording is still a serious problem

(5) CyberHand is so cool that DoD needs to start a competative project

(6) robot hand is good, but we need to work on tactile feedback

(7) we are still shooting in the dark

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When talking about the Mean Time To Failure (inverse or FITS, or failures per billion hours) the “bathtub” curve comes to mind. This curve represents a probability distribution for device failure, where you have a high rate of failure due to infant mortality, then a flat probability of random faliures, and finally an increased failure probability due to old age. National Semi has a pretty good overview of experimentally determining this distribution and the tests involved. The curiosity lies in looking at reliability reports, say for the AT49BV020, that show zero failures over a number of device hours but they are able to provide a predicted device failure rate. Since the normal MTTF formula (one involving at least one device failure, near the middle of the National link) would go to infinity, another method is employed. The Chi-squared distribution is used to determine the predicted failure rate for a device with no failures for a given operating hours and a given confidence (typically 60% or 90%.) Finally, ATMEL has a chapter (chapter 6) in their Quality and Reliability Handbook devoted to modeling device failures, especially when accelerating device failure with increased temperature or voltage.

( doc1281.pdf ) ( 49bv020.pdf ) ( calculating_mttf_with_zero_failures.pdf )

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If you ever needed a ruler and all you had was a printer, this site can be pretty useful. Various sizes and types, even goes up to meter-stick.

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Some years ago, I learned how to design analog filters to meet certain frequency response criteria which I then briefly used and then left to rot in the back of my brain. Being in need of this information again, I started reading about pole-zero filter design and analysis and found this application note to be both basic and well written. If you forgot the math behind filter design, this is a good refresher.

( an733.pdf )

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One of my favorite game lines was the Space Quest saga from Sierra. This was one of the original RPGs for the PC platform that involved humor, even at the time of death. By various accounts, this game is considered abandonware, so I do not think that me putting it up is really robbing Sierra of due revenue. Without further adeu, here is the first installment, I hope I don’t get sued.

( Space_Quest_1.1986.zip (extract and run Sierra.com))

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In one of my CMOS IC design classes, I spent almost a third of a semester looking at the various causes of latch-up and what preventative measures can be taken to avoid this nasty phenomenon. After having spent so much time (and money on a book) I was pleased to see this application note from TI: Latch-Up, ESD, and Other Phenomena by Eilhard Haseloff.

( slya014a.pdf )

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