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Member Since: January 4, 2011

Country: United States

  • Not that I usually do any better, but I couldn't help but notice that the digital I/O 0-7 pin header is slightly crooked in your product sample photos :-)

  • Nice catch... funny that it's been 4y and they haven't fixed that little transposition!

  • MCP23017

    Maybe because as a 16-pin PDIP instead of a 28-pin SPDIP, you can more easily fit one of these on a mini-breadboard along with your MCU module (typically 30 positions long, but may need to waste a couple for overhanging parts). Probably not cost... the '017 is only a few cents more (if you're buying 5k of them, anyway).

    I appreciate your pointing out the 16-port version, though... I'll keep that in mind if I ever need to control all the things!

  • Yet another library: https://github.com/davidhbrown/RealTimeClockDS1307
    Includes example sketch that (via Serial monitor) allows you to set the clock, accurately toggle AM/PM, enable/disable the square wave generator, and read/write memory.
    I wanted to use the square wave output to trigger an interrupt and use the battery-backed RAM for a data logger project, so I needed a library that would do a little more than just read the time.

  • Bad bootloader in the Uno I received in April 2011... problem had been fixed back in May 2010 per http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1287435600 but I guess the Italians didn't want Unos to be able to load sketches over 30k badly enough to incorporate it.
    Various methods of installing a good bootloader are available depending on what additional hardware you have. The method I used is described here: http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1295516707
    Would be good if Sparkfun could let us know when they have stock with updated bootloaders. If my professor hadn't had a spare Duemilanove to reprogram the Uno, I would have been stuck.

  • I'd like to use the 1Hz oscillator and the "open drain" SQW pin with an LED and resistor connected in series to the 5V supply.
    So far, I'm using a 3K-Ohm resistor to limit the LED to about 1mA (fairly dim). Is this sufficient as a pull-up resistor? A lower value / brighter LED would be nice. A 200-ohm resistor did also work, but I didn't leave it running for a long time. Should I be doing something else, like using SQW to drive my own transistor to switch the LED? Seems redundant, but I'd rather put in an extra part than kill the clock. I can't find anything in the datasheet that refers to allowable current on this pin; presumably it has no problem with the +5V it uses itself.
    All the online references to open drains (mostly talking about open collectors actually) I can find seem to be talking about using values up to hundreds of kohm to try to minimize current or dropping back maybe to 4.7kOhm for something like I2C running lots of parallel devices at 400kHz.
    The intended application is to help confirm running status of a data logger and so will be blinking away for months on end. I can also leave off the blinky without impairing the essential operation if I'm totally missing the intended use of the pin.

  • I also had trouble with poor contact on this shield -- the power light would illuminate only in very specific positions of insertion. I added stackable headers from Sparkfun's kit. I did check for shorts between all pin combinations and found connections only between the three ground pins. Also checked that there was a good connection between the +3.3V header pin and the hole next to it.
    I believe (but time will tell) I have solved the problem by making slight bends in the pins of the headers so they make better contact with the headers on the Uno. Using a small pliers, I bent the pins outward very slightly about 5mm from their tips and then back into position about 2mm from their tips.
    (Or possibly the fact that I had also plugged my soldering iron back in made it feel threatened enough to start working...)

No public wish lists :(