,
Table 155. Pin Values Used to Enter Programming Mode
Pin
PAGEL
XA1
Symbol
Value
Prog_enable[3]
Prog_enable[2]
Prog_enable[1]
Prog_enable[0]
0
0
0
0
XA0
BS1
Table 156. XA1 and XA0 Enoding
XA1
XA0
Action when XTAL1 is Pulsed
0
0
Load Flash or EEPROM Address (High or low address byte
determined by BS2 and BS1).
0
1
1
1
0
1
Load Data (High or Low data byte for Flash determined by BS1).
Load Command
No Action, Idle
Table 157. Command Byte Bit Encoding
Command Byte
1000 0000
0100 0000
0010 0000
0001 0000
0001 0001
0000 1000
0000 0100
0000 0010
0000 0011
Command Executed
Chip Erase
Write Fuse bits
Write Lock bits
Write Flash
Write EEPROM
Read Signature Bytes and Calibration byte
Read Fuse and Lock bits
Read Flash
Read EEPROM
Table 158. No. of Words in a Page and No. of Pages in the Flash
No. of
Flash Size
Page Size
PCWORD
Pages
PCPAGE
PCMSB
128K words (256K bytes) 128 words
PC[6:0]
1024
PC[16:7]
16
Table 159. No. of Words in a Page and No. of Pages in the EEPROM
No. of
EEPROM Size
Page Size
PCWORD
Pages
PCPAGE
EEAMSB
4K bytes
8 bytes
EEA[2:0]
512
EEA[11:3]
11
340
ATmega640/1280/1281/2560/2561
2549A–AVR–03/05
ATMEL [ ATMEL ]
