Monthly Archives: August 2006

Design something cool with msp430, get a free TV and more (due 2nd October)

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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.

Calculating the MTTF with zero failures

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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 )

Filter primer from Dallas Semi

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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 )

A bit of nostalgia

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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))