MCU: ATmega644
Package: 40 pin PDIP
 
 1: PB0   T0    XCK0    PCINT8
 2: PB1   T1    CLKO    PCINT9
 3: PB2   AIN0  INT2    PCINT10
 4: PB3   AIN1  OC0A    PCINT11
 5: PB4   /SS   OC0B    PCINT12
 6: PB5   MOSI  PCINT13
 7: PB6   MISO  PCINT14
 8: PB7   USCK  PCINT15
 9: Reset
10: Vcc
11: Gnd
12: XTAL2
13: XTAL1
14: PD0   RXD0  PCINT24
15: PD1   TXD0  PCINT25
16: PD2   INT0  RXD1    PCINT26
17: PD3   INT1  TXD1    PCINT27
18: PD4   OC1B  XCK1    PCINT28
19: PD5   OC1A  PCINT29
20: PD6   ICP1  OC2B    PCINT30
21: PD7   OC2A  PCINT31
22: PC0   SCL   PCINT16
23: PC1   SDA   PCINT17
24: PC2   TCK   PCINT18
25: PC3   TMS   PCINT19
26: PC4   TDO   PCINT20
27: PC5   TDI   PCINT21
28: PC6   TOSC1 PCINT22
29: PC7   TOSC2 PCINT23
30: AVCC
31: Gnd
32: AREF
33: PA7   ADC7  PCINT7
34: PA6   ADC6  PCINT6
35: PA5   ADC5  PCINT5
36: PA4   ADC4  PCINT4
37: PA3   ADC3  PCINT3
38: PA2   ADC2  PCINT2
39: PA1   ADC1  PCINT1
40: PA0   ADC0  PCINT0

Summary:
The high-performance, low-power Microchip 8-bit AVR RISC-based microcontroller
64 KB ISP flash memory with read-while-write capabilities, 
2 KB EEPROM, 
4 KB SRAM, 
32 general purpose I/O lines, 
32 general purpose working registers, 
a JTAG interface for boundary-scan and on-chip debugging/programming, 
2 x 8-bit, 1 x 16-bit timer/counters with compare modes, 
6 PWM ñhannels
internal and external interrupts,
serial programmable USART, 
a universal serial interface (USI) with start condition detector, 
an 8-channel 10-bit A/D converter, 
programmable watchdog timer with internal oscillator, 
SPI serial port, 
five software selectable power saving modes. 

