Rainbow-electronics ATmega161L Manual de usuario descargar pdf (Pagina 122)

122

ATmega161(L)

1228C–AVR–08/02

Programming the EEPROM The programming algorithm for the EEPROM Data memory is as follows (refer to “Pro-

gramming the Flash” for details on command, address and data loading):

1. A: Load Command “0001 0001”.

2. H: Load Address High Byte ($00 - $01)

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

4. E: Load Data Low Byte ($00 - $FF)

L: Write Data Low Byte

1. Set BS to “0”. This selects low data.

2. Give WR

a negative pulse. This starts programming of the data byte. RDY/BSY

goes low.

3. Wait until to RDY/BSY

goes high before programming the next byte.

(See Figure 78 for signal waveforms.)

The loaded command and address are retained in the device during programming. For

efficient programming, the following should be considered:

• The command needs to be loaded only once when writing or reading multiple

memory locations.

• Address High byte only needs to be loaded before programming a new 256-word

page in the EEPROM.

• Skip writing the data value $FF, that is, the contents of the entire EEPROM after a

Chip Erase.

These considerations also apply to Flash, EEPROM and Signature bytes reading.

Figure 78. Programming the EEPROM Waveforms

$11 ADDR. HIGH ADDR. LOW DATA LOWDATA

XA1

XA2

BS1

XTAL1

RDY/BSY

RESET

+12V

BS2

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Rainbow-electronics ATmega161L Manual de usuario Pagina 122