Serial.begin(                       57600    ); 
 Serial.print ( _AVR_IOXXX_H_);
outputs the name of the include file (ex: iom328p.h )
from Arduino.app/Contents/Resources/Java/hardware/tools/avr/avr/include/avr
that defines
PINB, PINB0, DDRB, DDB0, PORTB,PORTB0 … TIFR0 … PCIFR, EISMK, INT0, GPIOR0 …, EECR, …
EE_READY_vect, RAMEND, E2END, FLASHEND,
FUSE_BODLEVEL0 ,
SIGNATURE_0, 1,2

ATmel Section 30 register Summary

This section has hi addresses at the top of the page,
all descriptions have low addresses at the top of the diagram
nFF stack
  .
  .
 
   FF   .
reserved
  .
   C7
   C6 USART DataUDR0 70
   C5 baudUBRR0H
   C4 rateUBRR0L
   C2 UCSR0C RXC0
RcvCmplt
Character
ready 		TXC0
Trnsmit
Complete 		UDRE0
UDR0
is
empty 		FE
Frame
error 		DOR0
Data
OverRun 		UPE0
Parity
Error 		U2X0
Double
speed 		MPCM0
Multi-processor
Communication
Mode
B4Timer/Counter2 OCR2BOutput Compare Register B
B3 OCR2AOutput Compare Register A
B2 TCNT2Counter
AF 
8C
8BTimer/Counter1 OCR1BHOutput Compare Register B
8A OCR1BL
89 OCR1AHOutput Compare Register A
88 OCR1AL
87 ICR1HInput Capture
86 ICR1L
85 TCNT1HCounter
84 TCNT1L
83 
82 TCCR1CFOC1A FOC1B-- - - --
81 TCCR1BICNC1ICES1-WGM13 WGM12CS12CS11CS10
80 TCCR1ACOM1A1 COM1A1COM1B1COM1B1 - - WGM11WGM10
   64 Power ReductionPRR PRTWIPRTIM2 PRTIM0 PRTIM1PRSPI PRUSART0PRADC
   60 WatchDog controlWDTCSR WDIFWDIE WDP3
prescaler 		WDCE
change		WDE
sysResEna 		WDP2
prescaler		WDP0
prescaler
35 55 Reset sourceMCUSR WDRF
WatchDog		BORF
BrownOut		EXTRFPORF
PowerOn
 
2E 4E SPI data SPDR 70
2D 4D SPI status SPSR SPIF
int
flag		WCOL SPI2X
2C 4C SPI Control SPCR SPIE
interrupt
enabled 		SPE
module
enable 		DORD
order		MSTRCPOLCPHASPR1SPR0
2B 4B GPIOR2Gen Purpose I/O register 2
2A 4A GPIOR1Gen Purpose I/O register 1
 
 
28 48 OCR0B Used by arduino lib delay(ms)
Timer/Counter0 Output Compare Register B
27 47 OCR0A Timer/Counter0 Output Compare Register A
26 46 OCR0A Timer/Counter0 (8-bit)
25 45 TCCR0BFOC0A FOC0B-- WGM02 CS02 CS00CS00
24 44 TCCR0ACOM0A1 COM0A0COM0B1COM0B0 - - WGM01WGM00
23 43 GTCCRTSM --- - - PSRASYPSRSYNC
TSM=1 halt Timer/Counters
TSM=0 start 		Reset Timer/Counter prescalers
 
1E 3E GPIOR0Gen Purpose I/O register 0
1F R31ZH
1E R30ZL
1D R29YH
1C R28YL
1B R27XH
1A R26XL
19 
18 
17 37 Timer
interrupt
controls 		TIFR2---- -OCF2BOCF2ATOV2
16 36 TIFR1--ICF1- -OCF1BOCF1ATOV1
15 35 TIFR0---- -OCF0BOCF0ATOV0
 
ATmega
Section 13		reading
i = PINB		Set using SBI or
DDRD = DDRD | B11111100; 		toggle pins
SBI PINxnI think
0B 25
Port D		PORTD PORTD7PORTD6PORTD5PORTD4PORTD3PORTD2PORTD1PORTD0
0A 24 DDRD
direction		DDRD7DDRD6DDRD5DDRD4DDRD3DDRD4DDRD3DDRD7
09 23 PINDPIND7PIND6PIND5PIND4PIND3PIND2PIND1PIND0
08 25
Port C		PORTC
na		PORTC6PORTC5PORTC4PORTC3PORTC2PORTC1PORTC0
07 24 DDRC
direction		DDRC6DDRC5DDRC4DDRC3DDRC4DDRC3DDRC7
06 23 PINCPINC6PINC5PINC4PINC3PINC2PINC1PINC0
05 25
Port B		PORTB PORTB7PORTB6PORTB5PORTB4PORTB3PORTB2PORTB1PORTB0
04 24 DDRB
direction		DDRB7DDRB6DDRB5DDRB4DDRB3DDRB4DDRB3DDRB7
03 23 PINBPINB7PINB6PINB5PINB4PINB3PINB2PINB1PINB0
no Port A 


27.7.14
0000 1000 Read Signature Bytes and Calibration byte
1. A: Load Command 0000 1000.
2. B: Load Address Low Byte, 0x00.
3. Set OE to 0, BS1 to 1. The Calibration byte can now be read at DATA.
4. Set OE to 1.


0000 0100 Read Fuse and Lock bits




27.7.5
EEPROM, the program data is latched into a page buffer. This allows one page of data to be programmed simultaneously.