Manual

119
ATmega161(L)
1228C–AVR–08/02
Enter Programming Mode The following algorithm puts the device in Parallel Programming mode:
1. Apply 4.5 - 5.5V between V
CC
and GND.
2. Set RESET
and BS pins to “0” and wait at least 500 ns.
3. Apply 11.5 - 12.5V to RESET
, and wait for at least 500 ns.
Chip Erase The Chip Erase will erase the Flash and EEPROM memories plus Lock bits. The Lock
bits are not reset until the Program memory has been completely erased. The Fuse bits
are not changed. A Chip Erase must be performed before the Flash is reprogrammed.
Load Command “Chip Erase”
1. SetXA1,XA0to“10”. This enables command loading.
2. Set BS1 to “0”.
3. Set DATA to “1000 0000”. This is the command for Chip Erase.
4. Give WR
a negative pulse. This starts the Chip Erase. RDY/BSY goes low.
5. Wait until RDY/BSY
goes high before loading a new command.
PAGEL PD7 I Program Memory Page Load
BS2 PA0 I Byte Select 2 (Always low)
DATA PB7 - 0 I/O Bi-directional Data Bus (Output when OE is low)
Table 43. XA1 and XA0 Coding
XA1 XA0 Action when XTAL1 is Pulsed
00
Load Flash or EEPROM Address (High or low address byte determined by BS1)
01
Load Data (High or low data byte for Flash determined by BS1)
10
Load Command
11
No Action, Idle
Table 44. 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
0000 1000 Read Signature Bytes
0000 0100 Read Fuse and Lock bits
0000 0010 Read Flash
0000 0011 Read EEPROM
Table 42. Pin Name Mapping
Signal Name in
Programming Mode Pin Name I/O Function