Datasheet

346
ATmega640/1280/1281/2560/2561
2549K–AVR–01/07
When pulsing WR or OE, the command loaded determines the action executed. The dif-
ferent commands are shown in Table 161.
Figure 138. Parallel Programming
(1)
Note: 1. Unused Pins should be left floating.
Table 157. 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 W rite Pulse (Active low).
BS1 PD4 I Byte Select 1.
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.
DATA PB7-0 I/O Bi-directional Data bus (Output when OE is low).
Table 158. 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
VCC
+5V
GND
XTAL1
PD1
PD2
PD3
PD4
PD5
PD6
PB7 - PB0 DATA
RESET
PD7
+12 V
BS1
XA0
XA1
OE
RDY/BSY
PAGEL
PA0
WR
BS2
AVCC
+5V