Rainbow Electronics ATmega128L - Manual (Page 283)

283
ATmega128(L)
2467B–09/01
Table 121. 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 Bidirectional Data bus (Output when OE is low)
Table 122. 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 123. 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 124. 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