ATmega165 datasheet(252/336 Pages) ATMEL

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252

ATmega165/V

2573G–AVR–07/09

Parallel Programming

Enter Programming Mode

The following algorithm puts the device in parallel programming mode:

Apply 4.5 - 5.5V between V

CC and GND.

Set RESET to “0” and toggle XTAL1 at least six times.

Set the Prog_enable pins listed in Table 108 on page 251 to “0000” and wait at

least 100 ns.

Apply 11.5 - 12.5V to RESET. Any activity on Prog_enable pins within 100 ns

after +12V has been applied to RESET, will cause the device to fail entering pro-

gramming mode.

Wait at least 50 µs before sending a new command.

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.

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”

Set XA1, XA0 to “10”. This enables command loading.

Set BS1 to “0”.

Set DATA to “1000 0000”. This is the command for Chip Erase.

Give XTAL1 a positive pulse. This loads the command.

Give WR a negative pulse. This starts the Chip Erase. RDY/BSY goes low.

Wait until RDY/BSY goes high before loading a new command.

Programming the Flash

The Flash is organized in pages, see Table 105 on page 249. 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 pro-

gram the entire Flash memory:

A. Load Command “Write Flash”

Set XA1, XA0 to “10”. This enables command loading.

Set BS1 to “0”.

Set DATA to “0001 0000”. This is the command for Write Flash.

Give XTAL1 a positive pulse. This loads the command.

B. Load Address Low byte

ATmega165 Datasheet(PDF) 252 Page - ATMEL Corporation

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