ATMEGA640 datasheet(334/436 Pages) MICROCHIP

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334

ATmega640/V-1280/V-1281/V-2560/V-2561/V [DATASHEET]

DS40002211A

1. Set BS2, BS1 to “00”.

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 30-4 for signal

waveforms).

Figure 30-4. Programming the EEPROM Waveforms

30.7.6

Reading the Flash

The algorithm for reading the Flash memory is as follows (refer to “Programming the Flash” on page 331 for details

on Command and Address loading):

1. A: Load Command “0000 0010”.

2. H: Load Address Extended Byte (0x00- 0xFF).

3. G: Load Address High Byte (0x00 - 0xFF).

4. B: Load Address Low Byte (0x00 - 0xFF).

5. Set OE to “0”, and BS1 to “0”. The Flash word low byte can now be read at DATA.

6. Set BS to “1”. The Flash word high byte can now be read at DATA.

7. Set OE to “1”.

30.7.7

Reading the EEPROM

The algorithm for reading the EEPROM memory is as follows (refer to “Programming the Flash” on page 331 for

details on Command and Address loading):

1. A: Load Command “0000 0011”.

2. G: Load Address High Byte (0x00 - 0xFF).

3. B: Load Address Low Byte (0x00 - 0xFF).

4. Set OE to “0”, and BS1 to “0”. The EEPROM Data byte can now be read at DATA.

5. Set OE to “1”.

30.7.8

Programming the Fuse Low Bits

The algorithm for programming the Fuse Low bits is as follows (refer to “Programming the Flash” on page 331 for

details on Command and Data loading):

1. A: Load Command “0100 0000”.

2. C: Load Data Low Byte. Bit n = “0” programs and bit n = “1” erases the Fuse bit.

3. Give WR a negative pulse and wait for RDY/BSY to go high.

RDY/BSY

RESET +12V

PAGEL

BS2

0x11

ADDR. HIGH

DATA

ADDR. LOW

DATA

ADDR. LOW

DATA

XA1

XA0

BS1

XTAL1

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