AT90PWM2 datasheet(296/365 Pages) ATMEL

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296

AT90PWM2/3

4317B–AVR–02/05

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 127 on page 294. 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

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 “01”. 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 “01”. 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 138 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 137 on page 297. Note

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

the most significant bit(s) in the address low byte are used to address the page when

performing a Page Write.

G. Load Address High byte

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

Set BS1 to “1”. This selects high address.

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

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

H. Program Page

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