Datasheet

299
ATmega169A/PA/329A/PA/649A/P/3290A/PA/6490A/P [DATASHEET]
8284E–AVR–02/2013
1. Apply 4.5 - 5.5V between V
CC
and GND.
2. Set RESET
to “0” and toggle XTAL1 at least six times.
3. Set the Prog_enable pins listed in Table 28-10 on page 298 to “0000” and wait at least 100ns.
4. Apply 11.5 - 12.5V to RESET
. Any activity on Prog_enable pins within 100ns after +12V has been applied to
RESET
, will cause the device to fail entering programming mode.
5. Wait at least 50µs before sending a new command.
28.7.2 Considerations for Efficient Programming
The loaded command and address are retained in the device during programming. For efficient programming, the
following should be considered.
• The command needs only be loaded once when writing or reading multiple memory locations
• Skip writing the data value 0xFF, that is the contents of the entire EEPROM (unless the EESAVE Fuse is
programmed) and Flash after a Chip Erase
• Address high byte needs only be loaded before programming or reading a new 256 word window in Flash or 256
byte EEPROM. This consideration also applies to Signature bytes reading
28.7.3 Chip Erase
The Chip Erase will erase the Flash and EEPROM
(1)
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 and/or EEPROM are reprogrammed.
Note: 1. The EEPRPOM memory is preserved during Chip Erase if the EESAVE Fuse is programmed.
Load Command “Chip Erase”
1. Set XA1, XA0 to “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 XTAL1 a positive pulse. This loads the command.
5. Give WR
a negative pulse. This starts the Chip Erase. RDY/BSY goes low.
6. Wait until RDY/BSY
goes high before loading a new command.
28.7.4 Programming the Flash
The Flash is organized in pages, see Table 28-7 on page 296. When programming the Flash, the program data is
latched into a page buffer. This allows one page of program data to be programmed simultaneously. The following
procedure describes how to program the entire Flash memory:
A. Load Command “Write Flash”
1. Set XA1, XA0 to “10”. This enables command loading.
2. Set BS1 to “0”.
3. Set DATA to “0001 0000”. This is the command for Write Flash.
4. Give XTAL1 a positive pulse. This loads the command.
B. Load Address Low byte
1. Set XA1, XA0 to “00”. This enables address loading.
2. Set BS1 to “0”. This selects low address.
3. Set DATA = Address low byte (0x00 - 0xFF).
4. Give XTAL1 a positive pulse. This loads the address low byte.