ATtiny167-ESSZ datasheet(232/282 Pages) ATMEL

232 / 282 page

232

7728D–AVR–07/09

ATtiny87/ATtiny167

21.7.4

Programming the Flash

The Flash is organized in pages, see Table 21-7 on page 228. 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”

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

Set BS1 to “0”.

Set DATA to “0001 0000

b”. This is the command for Write Flash.

Give XTAL1 a positive pulse. This loads the command.

B. Load Address Low byte

Set XA1, XA0 to “00”. This enables address loading.

Set BS1 to “0”. This selects low address.

Set DATA = Address low byte (0x00 - 0xFF).

Give XTAL1 a positive pulse. This loads the address low byte.

C. Load Data Low Byte

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

Set DATA = Data low byte (0x00 - 0xFF).

Give XTAL1 a positive pulse. This loads the data byte.

D. Load Data High Byte

Set BS1 to “1”. This selects high data byte.

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

Set DATA = Data high byte (0x00 - 0xFF).

Give XTAL1 a positive pulse. This loads the data byte.

E. Latch Data

Set BS1 to “1”. This selects high data byte.

Give PAGEL a positive pulse. This latches the data bytes. (See Figure 21-3 for signal

waveforms)

F. Repeat B through E until the entire buffer is filled or until all data within the page is loaded.

While the lower bits in the address are mapped to words within the page, the higher bits

address the pages within the FLASH. This is illustrated in Figure 21-2 on page 233. Note that

if less than eight bits are required to address words in the page (pagesize < 256), the most sig-

nificant bit(s) in the address low byte are used to address the page when performing a Page

Write.

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