Wednesday, December 8, 2010

Troubleshooting Wise Clock 2

It happened to me (and to others as well) that sometimes, after uploading the sketch, Wise Clock 2 displays the message "Failed to read quotes.txt from SD card" even though the SD card is inserted and has the right files on it. Obviously, this is a problem. First impulse is to try another SD card (and another and another). Still same error. Panic.

Here is a list of points to follow in this case.
  • check that all components are soldered (believe it or not, it happened to me once that I forgot to solder the 3V3 voltage regulator);
  • check that all pins of the SD socket are soldered; since the kit comes with the SD card socket already soldered (by myself), any un-soldered pins is my fault (I apologize in advance if that happens; it did happen);
  • with the multimeter, check all connections to the SD socket;
  • make sure that the resistors in the voltage divider (4K7 and 10K, under the microcontroller) are correctly placed, as shown in photo 4 in the posting "Assembling Duino644".

Here is a tip on how to find out easily the polarity of a LED (especially useful for SMDs, either in circuit or not): with the multimeter's switch on the "check continuity" position (beeps), measure the "continuity" of the LED. The correct polarity will make the LED light up faintly.

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