ATtiny167 datasheet(231/282 Pages) ATMEL

231 / 282 page

231

7728D–AVR–07/09

ATtiny87/ATtiny167

21.7

Parallel Programming

21.7.1

Enter Programming Mode

The following algorithm puts the device in parallel programming mode:

Apply 4.5 - 5.5V between Vcc and GND.

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

Set the Prog_enable pins listed in Table 21-10 on page 230 to “0000

b” 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 programming

mode.

Wait at least 50 µs before sending a new command.

21.7.2

Considerations for Efficient Programming

The loaded command and address are retained in the device during programming. For effi-

cient 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.

21.7.3

Chip Erase

The Chip Erase will erase the Flash and EEPROM

(Note:) 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:

The EEPRPOM memory is preserved during Chip Erase if the EESAVE Fuse is programmed.

Load Command “Chip Erase”

Set XA1, XA0 to “1,0 ”. This enables command loading.

Set BS1 to “0”.

Set DATA to “1000 0000

b”. 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.

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