Rainbow Electronics ATmega128RFA1 - Manual (Page 470)

470
8266A-MCU Wireless-12/09
ATmega128RFA1
31.7.2 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.
31.7.3 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 EEPROM 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 CLKI 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.
31.7.4 Programming the Flash
The Flash is organized in pages; see Table 31-7 on page 467. 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 CLKI 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 CLKI a positive pulse. This loads the address low byte.