Hi,
The link to the ATmega168 datasheet is broken on e.g:
Datasheet Catalog seems to have one: ATMEGA168 Datasheet pdf - 16K Byte self-programming Flash Program Memory, 1K Byte SRAM, 512 Bytes EEPROM, 8 Channel 10-bit A/D-converter(TQFP/MLF). debugWIRE On-chip Debug System. Up to 24 MIPS throughput at 24 MHz. 1.8 - 5.5 Volt Operation (ATmega168V). - Atmel