January 13, 2012
about 3 years ago
SINGLE CHARACTER TYPO BUG IN V2 CODE: Fix increases the V2 logging rate by 7.5x.
The bug is described at the end of the above SFE forum post, with the test in the following post in the thread.
Anyone know the procedure for submitting a diff or patch or getting a git pull?
A good card to use is the very inexpensive Patriot 2GB model PSF2GMCSD, available for $1-$3 online (+ shipping), or $4-$6 in stores (Best Buy, WalMart & Fry’s have done selective internet price matching, but only with very reputable sites such as Amazon).
For speed, it meets or beats cards I’ve tried from SanDisk, Kingston, and RiData. For power consumption, it meets or beats Kingston and RiData (I get up to 15% longer V2 battery life with it). YMMV: I tried only one card of each brand. RiData and Kingston, in particular, can have significant performance swings between lots.
This card comes formatted in FAT32, so you will need to reformat it prior to use.
If your uSD card has been used before, be sure to avoid doing a ‘quick’ format, as this will merely deallocate previously-used sectors, not erase them, making the run-time performance truly suck since those sectors will need to be erased prior to being re-written.
If your uSD card is of an older generation (lacking deep ECC support and/or automatic bad-block detection), or has been completely filled hundreds of times, be sure to do a bad block scan on it.
V2 Oscillator Questions:
Which of Q1 or Q2 is more stable with temperature?
Which of Q1 or Q2 is more accurate (better calibrated at time of assembly, more likely to be closer to nominal spec value)?
Got the forced format to work: The card shows only a single 2GB FAT16 partition. But when put in the V2 and powered up on battery, both the red and green status LEDs came on steady.
Recommendation: Include a small known-good uSD card with the V2 (your margin should be OK for it), or at least keep one in stock. Or at the very least provide links to known-good devices.
Having a new SparkFun device I can’t yet use is a bummer.
The manual doesn’t even discuss this device limitation. Even a single sentence would have helped.
I have a 4GB Class 4 Kingston uSD card. Will it work in the V2 if I force-format it for FAT16 (2GB) and ignore the rest of the space?
If so, any recommendations for how to do this under Linux? (I can also get access to a Windows machine if needed.) I’ve tried the obvious ways, but the original FAT32 filesystem stubbornly refuses to go away…
Tutorial - Beginning Embedded Electronics - 9
about 3 years ago
GBO: Gerber Bottom Overlay, i.e. the silk screen for the bottom layer. If you put nothing there, the file will be blank, and may generate errors when read by a Gerber viewer. The tutorial mentions that it often costs extra to get silk-screening done on a second side, so it is seldom used unless absolutely necessary. If only a little text is needed on the bottom layer (such as a date), the tutorial mentions putting it in the copper.
GTO: A really great Pontiac car from the late ‘60’s. And the Gerber Top Overlay, which is the silk screen.
GTL/GBL: Top/Bottom copper (dunno why “L” is used).
GTS/GBS: Soldermask. This layer covers nearly all of the board (except where solder needs to go), and is what gives boards those cool colors (green is most common, SparkFun uses red).
Great tutorial! Thanks!
It inspired me to see how many vias I could remove: I got rid of them all, and the tutorial part placement was close to ideal to support it, but I got spaghetti traces as a result. To make it work as a single-sided board, I’d need to flip the USB connector to the non-copper side (and re-route the board) in order solder its pins.
Before going to layout I played with Tools->ERC, and it caught the USB GND error, which I fixed by adding the pin to the GND net. And before generating the Gerbers I ran Tools-DRC, which caught some traces that were placed too close to other copper (possible solder bridges or crosstalk if not fixed).
Wish-list item #1: How to do copper power and ground planes in Eagle? I fear my GND spaghetti trace could cause ground loops, which is probably not an issue here, but it could ruin an analog circuit.
Wish-list item #2: What do the Eagle layer names mean in English?
Tip: Write dates in the form: ddMMMyyyy (e.g., 16JAN2012) to avoid making folks in other countries wonder if 1-2-2012 is January 2nd (USA) or February 1st (rest of the world).
No public wish lists :(
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