Sunday, March 25, 2012

Troubleshooting guide for Wise Clock 3/4

This should really be a chapter of the assembling instructions for Wise Clock 3/4. Until I integrate everything into a single document, it is just another post that begged to be written (long ago, as a matter of fact).

1. Right after power up, the clock should make a beeping sound. If that does not happen, here are possible causes:
  • missing input 5V power; the optional power LED may be useful in this case, turned on when the power is present;
  • reset pin may be shorted to ground (the processor won't execute any code);
  • processor may not be powered: check that pin 10 has 5V and pin 11 is connected to ground;
  • faulty or missing the 16MHz clock for the processor; check crystal connections to the pins; if everything looks good electrically, try to upload a sketch; it that still doesn't work, test by replacing the processor or replacing the crystal;
  • buzzer may be disconnected; check connections between processor's pins and buzzer, shorts to the ground, terminal soldering.

2. The display does not light up at all (assuming the display is not defective):
  • faults in the connections to the display (right-hand header): look for shorts between neighbor pins in the display header; look for shorts between any signal pins in the display connector and ground;
  • output header (left-hand) display header may have shorts between neighbor pins or pins shorted to the ground;
  • the board's female connectors may be misaligned (shifted by one) when plugged in the display's male headers.

3. Getting SD card error in "Quote" mode:
  • faulty SD card; check the SD card itself by reading it in a PC; must be formatted FAT16 (therefore 2GB or smaller);
  • the required text files may be missing; check for their presence in the root directory;
  • SD card may not be powered; check 3V3 power on the third pin from the left (second pin from the left is connected to the ground);
  • check voltage divider resistors R5, R6, R7 (under the processor) and make sure they are 4K7.

4. Pressing a buttons (Set, Menu or Plus) does not trigger the expected action:
  • button itself may be defective, either always open (there is no contact between button's terminals when button is pressed) or always closed (short between terminals); verify with a multimeter that the button works correctly;
  • look for potential shorts between the "active" terminal (connected to the processor pins D0, D1 and D2/D3, see schematic) and ground.

5. Communication error when trying to upload a sketch:
  • make sure you plugged the FTDI cable/breakout the correct way/orientation, with the Ground/Black terminal to the right;
  • check the Rx/Tx connections to the processor (pins 14 and 15); make sure that they are not cut or shorted to the ground;
  • "stk500_getsync(): not in sync: resp=0x00 error" usually indicates that the upload speed is incorrect; for the ATmega644P processor, the upload speed must be 38400 (defined as atmega644.upload.speed=38400 in boards.txt); for the ATmega1284P processor, the upload speed is 57600;
  • if you get "avrdude: Yikes!  Invalid device signature. Double check connections and try again, or use -F to override this check", temporarily modify the signature in file hardware/tools/avr/avr/etc/avrdude.conf with one of these (depending on your processor):
    • signature = 0x1e 0x96 0x0a;   //  for ATmega644P
    • signature = 0x1e 0x97 0x05;   //  for ATmega1284P


  1. I got the SD Card error. Solved the problem (Windows 7) by formating as FAT with an allocation size of 64K. The windows default for FAT 16 is 32K.