194
8008H–AVR–04/11
ATtiny48/88
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.
21.2.3
Chip Erase
A Chip Erase must be performed before the Flash and/or EEPROM are reprogrammed. The
Chip Erase command will erase all Flash and EEPROM plus lock bits. If the EESAVE fuse is
programmed, the EEPROM is not erased.
Lock bits are not reset until the program memory has been completely erased. Fuse bits are not
changed.
The Chip Erase command is loaded as follows:
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
21.2.4
Programming the Flash
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 CLKI 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).
4.
Give CLKI 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).