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October 13, 2009
News - Why You Should De-Rate Ca…
about 2 years ago
Stumbled across this article and there’s a few too many generalities and not enough background…
Derating ceramic capacitors is mostly done for the effect of capacitance loss as voltage increases, but the critical point is that different physical -sizes- have dramatically different rates of change. A 1206 SMD cap will lose rated capacitance much more slowly than a 0603 as the voltage rises (oddly enough, a 0603 cap probably won’t have anywhere near the rated capacitance even at 50% the “rated” voltage, whereas a 1206 will probably be very close to the rated capacitance at 50% rated voltage)
In typical microcontroller circuits, where a single stable DC voltage is all that is ever expected, Tantalum capacitors make perfect sense and there’s absolutely no reason to shy away from them. Tantalums also don’t suffer significantly from voltage derating, so they can be relied upon to deliver a specific capacitance more or less right up to the rated voltage.
Tantalums are also a prerequisite in a lot of low-dropout voltage regulator applications, the ESR of ceramics is too low, and electrolytics are impractical.
Yes, Tantalums can go “pop” if connected in reverse and over-volted, but if you do things like that, the rest of the circuit is probably toast as well, so at least you know -right away- you did a bad thing! ;)
about 2 years ago
Ah! Got it, must have been looking at the wrong file…
Is it possible to re-map the Serial0 UART to any of the other available pins to allow two hardware UARTs and SPI/I2C? (realizing that this reduces available pins pretty far!)
I was looking though the “variant” files for the SAMD21 mini breakout and I can’t see where the re-mapping was done (it all appeared to be Zero defaults). Can you show us how the remap was done?
Maybe I’m looking at the wrong package…
Ordered two of these, and although I’m not 100% sure, it looks like the SPI port that is implemented is not the default one that is used by the Arduino IDE.
The Zero schematic suggests that the SPI port on pins: PB10, PB11 and PA12 is the default. Perhaps someone can confirm?
Also, the RX/TX map to what is essentially the “second” serial port; SERIAL1. PB22 and PB23 are the default SERIAL0. The schematic suggests that SERIAL0 is connected to the EDBG header, but it’s not clear which pins would be used.
News - IP Obesity
about 5 years ago
To re-iterate what a lot of people are saying, but some are missing, very little that SparkFun manufactures would ever be patentable, so “open source” is kind of a no-brainer!
SparkFun makes very good “datasheet applications” of various ICs and components, but hardly anything that would ever be provided patent protection.
Trying to patent a circuit made from off-the-shelf components would be near-impossible. The circuit itself may be covered by copyright, but it’s trivially easy to reverse engineer and change a few things and have exactly the same functionality, and not be infringing.
Software (or firmware) is the magic sauce that give significant value to commodity boards and sensors, and that’s one kind of IP that you can control to a degree, and takes significantly more effort to reverse-engineer.
The underlying problem here is trying to overreach with “open source”, and apply it to tech IP in general. IP protection is an absolute requirement where millions of dollars of R&D are at stake, but meaningless when it’s a board or device that can be designed by an amateur in a few hours. (I could (and have) easily design an Arduino-compatible board from scratch in a few hours in Eagle…)
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