ATmega16 datasheet(259/315 Pages) ATMEL

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259

ATmega16(L)

2466E–AVR–10/02

Parallel Programming

Enter Programming Mode

The following algorithm puts the device in Parallel Programming mode:

Apply 4.5 - 5.5V between V

CC and GND, and wait at least 100 µs.

Set RESET to “0” and toggle XTAL1 at least 6 times

Set the Prog_enable pins listed in Table 107 on page 258 to “0000” and wait at

least 100 ns.

Apply 11.5 - 12.5V to RESET. Any activity on Prog_enable pins within 100 ns

after +12V has been applied to RESET, will cause the device to fail entering Pro-

gramming mode.

Note, if External Crystal or External RC configuration is selected, it may not be possible

to apply qualified XTAL1 pulses. In such cases, the following algorithm should be

followed:

Set Prog_enable pins listed in Table 107 on page 258 to “0000”.

Apply 4.5 - 5.5V between VCC and GND simultanously as 11.5 - 12.5V is applied

to RESET.

Wait 100 µs.

Re-program the fuses to ensure that External Clock is selected as clock source

(CKSEL3:0 = 0b0000) If Lock bits are programmed, a Chip Erase command

must be executed before changing the fuses.

Exit Programming mode by power the device down or by bringing RESET pin to

0b0.

Entering Programming mode with the original algorithm, as described above.

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 $FF, 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.

Table 111. No. of Words in a Page and no. of Pages in the EEPROM

EEPROM Size

Page Size

PCWORD

No. of Pages

PCPAGE

EEAMSB

512 bytes

4 bytes

EEA[1:0]

128

EEA[8:2]

ATMEGA16 Datasheet(PDF) 259 Page - ATMEL Corporation

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