AVR Project PCB - Application Note
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Base configuration components:
U1:         ATMEGA 8, 48, 88, 168 or 328 in a 28pin socket
C2, C3, C7: 100nF
C6:          >= 10uF
R1:         10k (Reset Pull-up)
SW1/RESET:  Momentary Micro Push Button
P3:         2x3pin connector to AVR ISP programmer
X1:         18.423MHz or prefered crystal
C4, C5:     22pF

Serial I/O Option: 
- Add serial to usb board to SER-USB in appropriate socket and connect via separate row of pins to VCC, PD1(AVR-TxD), PD0(AVR-RxD) and GND. 
-> Attention: Connect RxD of USB-SER to AVR-TxD and vice versa!

no Crystal Option:
- You may close jumper J4 and J5 to gain additional AVR I/O PB6 and PB7 column on project area.
- When jumper left open the corresponding "PB6 and PB7 AVR column" may be used for own purposes.

Reset on PC6 Option:
- You may close jumper J6 to use "AVR column" PC6 for AVR reset purposes. 
- When jumper is left open, the corresponding "PC6 AVR column" in project area may be used for own purposes.

External AREF Option:
- Jumper J16 must be closed when using "AREF column" from project area to feed AVR.
- When jumper is left open, the corresponding "AREF column" in project area may be used for own purposes.

ADC voltage stabilisation option:
- Add C1 = 100nF, open jumper J1 and add appropriate induction L1.


Power Supply Distribution

Only Vcc = 5V Option: 
- Connect Power via either Vcc connector (when there is more equipment needing Vcc, the small connector should be used to power that).
- Close jumper J2 and/or J3 to Vcc to distribute Vcc to project area as needed.
- When jumper is left open the corresponding "Vxx row" in project area may be used for own purposes

Vcc from Vbat via U2 Option:
- Add C9 = 100nF, C8 >= 10uF and U2 = 7805 (LM1117 or similar regulator). 
- Connect Vbat power via either Vbat connector (when there is more equipment needing Vbat, the small connector should be used to power that).
- Close jumper J2 and J3 to Vcc or Vbat to distribute Vcc and/or Vbat to project area correspondingly.
- If needed, close jumper J15 to let Vxx-row on project area become Vbat.

-> large power connector: VH 3.96mm
-> small power connector: KF2510 (also to be used for connector area on the top)


FET Transistor Option:

- The gate pins of Q1 to Q6 are wired to corresponding G1 to G6 on the top of the board, where they are nearby the column of the AVR's PWM output: 
G1 -> PD6 - OC0A (AIN0)
G2 -> PD5 - OC0B (T1)
G3 -> PB1 - OC1A
G4 -> PB2 - OC1B (/SS)
G5 -> PB3 - OC2A (MOSI), (one pin to the left) 
G6 -> PD3 - OC2B (INT1)
- When using N-type FET (IRL3705) at position Q1, Q3 and Q5, the source pin may connected to GND by setting jumper J9, J11 and J13 to GND correspondingly.
- If more N-type FET are needed, place them at postition Q2, Q4 and Q6. The source pin may become GND by setting jumper J10, J12 and J14 to GND correspondingly.
- For P-type FET (IRF4905) on position Q1, Q3 and Q5, the jumper J7 selects Vcc or Vbat to be connected to the source pin via corresponding jumper J9, J11 and J13 set to VJ7.
- Similar when using P-type FET on position Q2, Q4 and Q6: jumper J8 selects the voltage (Vcc or Vbat) to be connected to the source pin with corresponding jumper J10, J12 and J14 set to VJ8.
- When there is a (power)resistor needed in the drain path of Q1 to Q6, it can be placed at postition QxD to Ox nearby the corresponding FET Qx. The output leads to O1 - O6 on the upper, left corner near the connector area.