291
2467S–AVR–07/09
ATmega128
XA1
PD6
I
XTAL Action Bit 1
PAGEL
PD7
I
Program Memory and EEPROM data Page Load
BS2
PA0
I
Byte Select 2 (“0” selects low byte, “1” selects 2’nd
high byte)
DATA
PB7-0
I/O
Bi-directional Data bus (Output when OE is low)
Table 121.
Pin Values Used to Enter Programming Mode
Pin
Symbol
Value
PAGEL
Prog_enable[3]
0
XA1
Prog_enable[2]
0
XA0
Prog_enable[1]
0
BS1
Prog_enable[0]
0
Table 122.
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 123.
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
Table 120.
Pin Name Mapping (Continued)
Signal Name in
Programming Mode
Pin Name
I/O
Function
Содержание ATmega128
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