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295

2467S–AVR–07/09

ATmega128

Figure 137. Programming the Flash Waveforms

Note: “XX” is don’t care. The letters refer to the programming description above.

Programming the

EEPROM

The EEPROM is organized in pages, see Table 124 on page 292. When programming the

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

programmed simultaneously. The programming algorithm for the EEPROM data memory is as

follows (refer to “Programming the Flash” on page 293 for details on Command, Address and

Data loading):

1. A: Load Command “0001 0001”.

2. G: Load Address High Byte ($00 - $FF).

3. B: Load Address Low Byte ($00 - $FF).

4. C: Load Data ($00 - $FF).

5. E: Latch data (give PAGEL a positive pulse).

K: Repeat 3 through 5 until the entire buffer is filled.

L: Program EEPROM page:

1. Set BS1 to “0”.

2. Give WR

a negative pulse. This starts programming of the EEPROM page. RDY/BSY

goes low.

3. Wait until to RDY/BSY

goes high before programming the next page.

(See Figure 138 for signal waveforms.)

RDY/BSY

RESET +12V

PAGEL

BS2

0x10 ADDR. LOW

ADDR. HIGH

DATA

DATA LOW DATA HIGH ADDR. LOW DATA LOW DATA HIGH

XA1

XA0

BS1

XTAL1

XX XX

AB CDEB CDEGH

Atmel ATmega128 User Manual

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