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1. CPU Support

Solder the CPU support hardware from lowest profile part to highest. That way when the board is flipped over, the parts are pushed flush against the board.


RESISTORS : Start by soldering the resistors. The polarity (orientation) does not matter.


  • R1 to R16 : 100 Ohm [brown-black-brown]
  • R30 : 100 Ohm
  • R17,R18,R19,R22,R23,R31,[R36,R37,R38 not used] : 10k [brown-black-orange]
  • R20, R21 : 4k7 [yellow-violet-red]
  • R25,R26 : 1k [brown-black-red]
  • R33,R35 : 680E [blue-grey-brown]


IC SOCKETS : The sockets are polarized - so make sure to align them correctly with the legend marking on the board.  (If you happen to solder one of these in backwards, don't fret, just be sure to plug the IC as indicated on the board).

  • U3 : 28 pin socket, 0.3" width - for ATMega processor
  • U4 : 24 pin socket, 0.6" width - for Column Driver 74LS154
  • U5 : 16 pin socket, 0.3" width - for row driver STP8DP05


CAPACITORS : There is one polarized capacitor (C8), and all the others are non-polarized.

  • C3,C6,C9,C10 : 100nF decoupling/filtering capacitors
  • C8 : 100uF Electrolytic capacitor (polarized)


TRANSISTORS :  With transistors, orientation matters. The silk screen indicates the correct orientation. We find that using the middle hole is easier than using the offset hole.


  • Q1-Q17 2N5401 Near 100 Ohm resistors


Other Parts : Finish off by adding in all the other remaining pasts.


  • J1 (or J2 or J3) : The USB-b type Power Input socket. Use one of the three available locations depending on where you want the power cable to come out from.
  • K1, K2 : 3 pin male header pins for Power Select (Wall Wart or USB) and LED ARRAY (Enable or Disable). Both of these also require a shorting link.
  • P7 : 6 pin, right angle, male header pins for FTDI connector
  • R32 : LDR (light dependent resistor, may be supported in future release)
  • SP1 : Speaker / Buzzer
  • SW1,SW2,SW3,SW4,SW5 : right angle push button switches
  • X1 : 16MHz resonator (3 pins, not polarized)

  • Thumbwheel POT (5K).  Dimming Potentiometer (Pot) : The Dimming potentiometer allows manual control of the brightness of the LED array. There are a lot of solder pads for this component, to allow various different types of potentiometers to be used.  Whichever pot you use, try to make the control accessible from the top of the board (see photo).