ATtiny44 datasheet(169/236 Pages) ATMEL

169 / 236 page

169

8006H–AVR–10/09

ATtiny24/44/84

19.7.2

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.

19.7.3

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 re-

programmed.

Load command “Chip Erase” (see Table 19-16 on page 171).

Wait after Instr. 3 until SDO goes high for the “Chip Erase” cycle to finish.

Load Command “No Operation”.

Note:

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

19.7.4

Programming the Flash

The Flash is organized in pages, see “Page Size” on page 162. When programming the Flash,

the program data is latched into a page buffer. This allows one page of program data to be pro-

grammed simultaneously. The following procedure describes how to program the entire Flash

memory:

Load Command “Write Flash” (see Table 19-16 on page 171).

Load Flash Page Buffer.

Load Flash High Address and Program Page. Wait after Instr. 3 until SDO goes high for

the “Page Programming” cycle to finish.

Repeat 2 through 3 until the entire Flash is programmed or until all data has been

programmed.

End Page Programming by Loading Command “No Operation”.

When writing or reading serial data to the ATtiny24/44/84, data is clocked on the rising edge of

the serial clock, see Figure 20-6 on page 184, Figure 19-3 on page 167 and Table 20-13 on

page 184 for details.

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