Datasheet

251
7799D–AVR–11/10
ATmega8U2/16U2/32U2
PAGEL PD7 I Program Memory and EEPROM data Page Load.
BS2 PC6 I Byte Select 2.
DATA PB7-0 I/O Bi-directional Data bus (Output when
OE is low).
Table 25-10. BS2 and BS1 Encoding
BS2 BS1
Flash / EEPROM
Address
Flash Data
Loading /
Reading
Fuse
Programming
Reading Fuse
and Lock Bits
0 0 Low Byte Low Byte Low Byte Fuse Low Byte
0 1 High Byte High Byte High Byte Lockbits
10
Extended High
Byte
Reserved Extended Byte
Extended Fuse
Byte
1 1 Reserved Reserved Reserved Fuse High Byte
Table 25-11. 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 25-12. XA1 and XA0 Encoding
XA1 XA0 Action when XTAL1 is Pulsed
00
Load Flash or EEPROM Address (High or low address byte determined
by BS2 and 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 25-13. Command Byte Bit Encoding
Command Byte Command Executed
1000 0000 Chip Erase
0100 0000 Write Fuse bits
0010 0000 Write Lock bits
0001 0000 Write Flash
Table 25-9. Pin Name Mapping
Signal Name in
Programming Mode Pin Name I/O Function