ATMEGA640 datasheet(331/436 Pages) MICROCHIP

331 / 436 page

331

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

DS40002211A

30.7.2

Considerations for Efficient Programming

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

following should be considered.

•

The command needs only be loaded once when writing or reading multiple memory locations

•

Skip writing the data value 0xFF, that is the contents of the entire EEPROM (unless the EESAVE Fuse is

programmed) and Flash after a Chip Erase

•

Address high byte needs only be loaded before programming or reading a new 256 word window in Flash or

256 byte EEPROM. This consideration also applies to Signature bytes reading

30.7.3

Chip Erase

The Chip Erase will erase the Flash and EEPROM(1) memories plus Lock bits. The Lock bits are not reset until the

program memory has been completely erased. The Fuse bits are not changed. A Chip Erase must be performed

before the Flash and/or EEPROM are reprogrammed.

Note:

1. The EEPRPOM memory is preserved during Chip Erase if the EESAVE Fuse is programmed.

Load Command “Chip Erase”

1. Set XA1, XA0 to “10”. This enables command loading.

2. Set BS1 to “0”.

3. Set DATA to “1000 0000”. This is the command for Chip Erase.

4. Give XTAL1 a positive pulse. This loads the command.

5. Give WR a negative pulse. This starts the Chip Erase. RDY/BSY goes low.

6. Wait until RDY/BSY goes high before loading a new command.

30.7.4

Programming the Flash

The Flash is organized in pages, see Table 30-7 on page 328. 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”

1. Set XA1, XA0 to “10”. This enables command loading.

2. Set BS1 to “0”.

3. Set DATA to “0001 0000”. This is the command for Write Flash.

4. Give XTAL1 a positive pulse. This loads the command.

B. Load Address Low byte (Address bits 7:0)

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

2. Set BS2, BS1 to “00”. This selects the address low byte.

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

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

C. Load Data Low Byte

1. Set XA1, XA0 to “01”. This enables data loading.

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

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

ATMEGA640 Datasheet(PDF) 331 Page - Microchip Technology

ATMEGA640 Datasheet(HTML) 331 Page - Microchip Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL