ATMEGA640 datasheet(330/436 Pages) MICROCHIP

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

DS40002211A

30.7 Parallel Programming

30.7.1

Enter Programming Mode

The following algorithm puts the device in parallel programming mode:

1. Apply 4.5V - 5.5V between VCC and GND.

2. Set RESET to “0” and toggle XTAL1 at least six times.

3. Set the Prog_enable pins listed in Table 30-11 to “0000” and wait at least 100ns.

4. Apply 11.5V - 12.5V to RESET. Any activity on Prog_enable pins within 100ns after +12V has been applied

to RESET, will cause the device to fail entering programming mode.

5. Wait at least 50µs before sending a new command.

Table 30-11. Pin Values Used to Enter Programming Mode

Symbol

Value

PAGEL

Prog_enable[3]

XA1

Prog_enable[2]

XA0

Prog_enable[1]

BS1

Prog_enable[0]

Table 30-12. XA1 and XA0 Enoding

XA1

XA0

Action when XTAL1 is Pulsed

Load Flash or EEPROM Address (High or low address byte determined by BS2 and BS1)

Load Data (High or Low data byte for Flash determined by BS1)

Load Command

No Action, Idle

Table 30-13. Command Byte Bit Encoding

Command Byte

Command Executed

1000 0000

Chip Erase

0100 0000

Write Fuse bits

0010 0000

Write Lock bits

0001 0000

Write Flash

0001 0001

Write EEPROM

0000 1000

Read Signature Bytes and Calibration byte

0000 0100

Read Fuse and Lock bits

0000 0010

Read Flash

0000 0011

Read EEPROM

ATMEGA640 Datasheet(PDF) 330 Page - Microchip Technology

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