Datasheet

315
8284D–AVR–6/11
ATmega169A/PA/329A/PA/3290A/PA/649A/P/6490A/P
Table 28-9. Pin Name Mapping
Signal Name in
Programming Mode Pin Name I/O Function
RDY/BSY PD1 O
0: Device is busy programming, 1: Device is ready for
new command.
OE
PD2 I Output Enable (Active low).
WR
PD3 I Write Pulse (Active low).
BS1 PD4 I
Byte Select 1 (“0” selects low byte, “1” selects high
byte).
XA0 PD5 I XTAL Action Bit 0
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 28-10. 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 28-11. 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 28-12. 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