ATtiny261-ESSZ datasheet(176/227 Pages) ATMEL

176 / 227 page

176

7753C–AVR–07/09

ATtiny261/ATtiny461/ATtiny861

22.8

Parallel Programming

22.8.1

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 22-10 on page 175 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 programming mode.

Wait at least 50 µs before sending a new command.

22.8.2

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.

22.8.3

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 perfor med before the Flash and/or EEPROM are

reprogrammed.

Note:

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

Table 22-12. 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 and Calibration byte

0000 0100

Read Fuse and Lock bits

0000 0010

Read Flash

0000 0011

Read EEPROM

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