ProPOV Day 5

20 May, 2011

The bizarre lights

Wow. Today I soldered the final pieces onto the board, and ran into huge problems. There is good news and bad news:

Good:

  1. The ISP talks to the AVR correctly, and I burned the bootloader onto the chip.
  2. Some of the LEDs light up
  3. The voltage regulator puts out 5V

Bad:

  1. Plugged the board into a mislabelled power supply, and let the magic smoke out of the voltage regulator (oh no!)
  2. Got bizarre LED output from a seemingly-simple serial out command (see the video)
  3. The FTDI doesn’t work
  4. I have no idea where to start looking

The code seems okay, and the schematic looks correct. However, the oscilloscope shows a hideous CLK (register clock) signal that modulates all around and can’t stay steady. The result suggests an inadvertent RC circuit with painful oscillations.

workbench