Datasheet

222
ATmega8(L)
2486M–AVR–12/03
Parallel Programming
Parameters, Pin
Mapping, and
Commands
This section describes how to parallel program and verify Flash Program memory,
EEPROM Data memory, Memory Lock Bits, and Fuse Bits in the ATmega8. Pulses are
assumed to be at least 250 ns unless otherwise noted.
Signal Names In this section, some pins of the ATmega8 are referenced by signal names describing
their functionality during parallel programming, see Figure 104 and Table 89. Pins not
described in the following table are referenced by pin names.
The XA1/XA0 pins determine the action executed when the XTAL1 pin is given a posi-
tive pulse. The bit coding is shown in Table 91.
When pulsing WR or OE, the command loaded determines the action executed. The dif-
ferent Commands are shown in Table 92.
Figure 104. Parallel Programming
Table 89. 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
VCC
+5V
GND
XTAL1
PD1
PD2
PD3
PD4
PD5
PD6
PC[1:0]:PB[5:0]
DATA
RESET
PD7
+12 V
BS1
XA0
XA1
OE
RDY/BSY
PAGEL
PC2
WR
BS2
AVCC
+5V