iWRAP
-----
                        +---------------+        WT12
              5V        |   ATmega168   | 5V/3.3V~~~~
              +-----+---|Vcc,AVCC    PC4|---/--->iWRAP(RxD)
USB           |     C3  |            PC5|<--/----iWRAP(TxD)
~~~           |     +   |               | 
5V <--BATT    +    GND  |               |        HHKB
              R1        |               |        ~~~~
D- <----+-----+--R2-----|INT1      PB2-4|------->ROW(6-8)
D+ <----|---+----R3-----|INT0      PC0-2|------->COL(9-11)
        Z1  Z2          |            PC3|------->ENABLE(12)
GND<----+---+-----------|GND         PB0|<-------KEY(4)
                        |            PB1|------->PREV(5)
                        |               |
            GND+-C2--+--|XTAL1       RXD|------->Debug Console
                     X1 |            TXD|<-------Debug Console
            GND+-C3--+--|XTAL2       RST|---SW--+GND
                        +---------------+

R1:     1.5K Ohm
R2,R3:  68 Ohm
Z1,Z2:  Zener 3.6V
C1,C2:  22pF
C3:     0.1uF
X1:     Crystal 12MHz
SW:     Push Switch(Optional)
BATT:   Li-Po Battery, Battery Charger and Voltage Regulator(5V and 3.3V).