Member Since: April 26, 2009

Country: United States

  • I've used the BSS138 as a logic level shifter in several of my designs. I'm almost positive that's what Sparkfun uses in their designs.

  • How will horse drawn carriage drivers afford to buy all the fun stuff without jobs or money or the sense of societal identity currently provided to them by "their" (I'm speaking figuratively, of course, as they dont really own anything) jobs?
    I don't know. Maybe we'll eat all of them? (soylent green??)
    You're joking, right?
    Sure there are issues with the advancement of science and technology, but overall the result has been good. Somehow, I have a feeling that mankind will find a way.

  • To answer your other questions...
    Yes, the pullup resistors are included, so you don't need more. I haven't tried with Arduino/Atmega yet. For libraries, there's an i2c library for the arduino called Wire:

  • From the datasheet and schematic I see a possible issue for 3.3V systems. They connected all the pullup resistors and the chips VDD to the battery voltage (labeled VCC), however Figure 7 in the datasheet shows the connections should be tied to the 3.3V of the microcontroller and isolated from the battery’s voltage, which could fluctuate from 2.6V to 4.2V. I think this could mean up to 4.2V signal levels on the 3.3V chip, but I’m not sure if this would actually cause a problem. Maybe try this out with a 5V Arduino? Looking at the signals with a logic probe or oscope might help. If I get I2C working on the datalogger (which runs at 3.3V) I’ll give this a try. Hopefully it’s just a code issue.

  • It's poorly documented, too.
    That's kind of silly to say. The schematic, board layout, and all the source code are provided. Every bit and byte, every wire and part is documented.
    My guess is that your SD card isn't formated correctly. I had a card that I thought was good. It wasn't, even though I could still read and write to the card through the logger as a mass storage device. I wouldn't trust the windows /FS:FAT option if it doesn't say "16" in the command. Your partition has to be 2GB or less. Maybe your battery supply isn't sufficient so the board can't operate correctly when you unplug the USB. Maybe you have a bad card or a bad board. You could also trying hooking up to the serial output to see what the debug messages say.

  • If you look on DigiKey, it's $21 for just the chip. While the Pololu looks like a great board, it can't handle the input voltage this can. Pololu has some that can handle 42V, but they can only supply .6A. I've spent the last couple weeks looking for options from TI, LT, MAXIM, on DigiKey and Mouser. This isn't a bad deal if it's what you need.

  • How easy would it be to open up the display and put in higher power LEDs?

  • I also had an almost 5V output using the schematics from the datasheet. When the sensor was cold, the sensing resistance was 1.8M ohms, but when it was heated, it was only 8K ohms. I tested a second device I bought, and discovered that it's sensing resistance was 10M ohms when cold (I haven't tried when it is hot yet). So either one device I bought was defective/severely different from the data sheet, or I damaged it when soldering onto the breakout board (maybe too much heat?).
    As you pointed out, a smaller pull down resistor should work, but I'll have to do some experiments to see if the sensor is still behaving correctly.

  • Good question, because I see on the Atmel site it says the ATiny13 is "Not recommended for new designs."

  • Do you have a recommended antenna? Is an active necessary? It would be nice if the GPS guide had a section covering antennas. Thanks

No public wish lists :(