ATMEGA8_08 Datasheet, PDF (227/308 Pages) ATMEL Corporation – 8-bit with 8K Bytes In-System Programmable Flash

ATmega8(L)
Table 91. Pin Name Mapping (Continued)
Signal Name in
Programming Mode
Pin Name
I/O
PAGEL
PD7
I
BS2
PC2
I
DATA
{PC[1:0]: PB[5:0]} I/O
Function
Program memory and EEPROM Data
Page Load
Byte Select 2 (“0” selects Low byte, “1”
selects 2’nd High byte)
Bi-directional Data bus (Output when OE is
low)
Table 92. Pin Values used to Enter Programming Mode
Pin
Symbol
PAGEL
Prog_enable[3]
XA1
Prog_enable[2]
XA0
Prog_enable[1]
BS1
Prog_enable[0]
Value
0
0
0
0
Table 93. XA1 and XA0 Coding
XA1 XA0 Action when XTAL1 is Pulsed
0
0 Load Flash or EEPROM Address (High or low address byte determined by BS1)
0
1 Load Data (High or Low data byte for Flash determined by BS1)
1
0 Load Command
1
1 No Action, Idle
Table 94. Command Byte Bit Coding
Command Byte
Command Executed
1000 0000
Chip Erase
0100 0000
Write Fuse Bits
0010 0000
Write Lock Bits
0001 0000
Write Flash
0001 0001
Write EEPROM
0000 1000
Read Signature Bytes and Calibration byte
0000 0100
Read Fuse and Lock Bits
0000 0010
Read Flash
0000 0011
Read EEPROM
2486T–AVR–05/08
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