ATMEGA48V_11 ATMEL [ATMEL Corporation], ATMEGA48V_11 Datasheet - Page 292

• Manufacturer Part Number: ATMEGA48V_11
• Description: 8-bit Atmel Microcontroller with 4/8/16K Bytes In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

28.7.2
28.7.3
28.7.4
2545T–AVR–05/11
Considerations for efficient programming
Chip erase
Programming the flash
4. Keep the Prog_enable pins unchanged for at least 10µs after the High-voltage has been
5. Wait until V
6. Exit Programming mode by power the device down or by bringing RESET pin to 0V.
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
• Address high byte needs only be loaded before programming or reading a new 256 word
The Chip Erase will erase the Flash and EEPROM
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:
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.
The Flash is organized in pages, see
the program data is latched into a page buffer. This allows one page of program data to be pro-
grammed 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
1. Set XA1, XA0 to “00”. This enables address loading.
2. Set BS1 to “0”. This selects low address.
3. Set DATA = Address low byte (0x00 - 0xFF).
EESAVE Fuse is programmed) and Flash after a Chip Erase
window in Flash or 256 byte EEPROM. This consideration also applies to Signature bytes
reading
applied to ensure the Prog_enable Signature has been latched.
commands.
1. The EEPRPOM memory is preserved during Chip Erase if the EESAVE Fuse is programmed.
CC
actually reaches 4.5V - 5.5V before giving any parallel programming
Table 28-9 on page
(1)
memories plus Lock bits. The Lock bits are
289. When programming the Flash,
ATmega48/88/168
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