296
2467S–AVR–07/09
ATmega128
Figure 138. Programming the EEPROM Waveforms
Reading the Flash The algorithm for reading the Flash memory is as follows (refer to “Programming the Flash” on
page 293 for details on Command and Address loading):
1. A: Load Command “0000 0010”.
2. G: Load Address High Byte ($00 - $FF).
3. B: Load Address Low Byte ($00 - $FF).
4. Set OE
to “0”, and BS1 to “0”. The Flash word low byte can now be read at DATA.
5. Set BS1 to “1”. The Flash word high byte can now be read at DATA.
6. Set OE
to “1”.
Reading the EEPROM The algorithm for reading the EEPROM memory is as follows (refer to “Programming the Flash”
on page 293 for details on Command and Address loading):
1. A: Load Command “0000 0011”.
2. G: Load Address High Byte ($00 - $FF).
3. B: Load Address Low Byte ($00 - $FF).
4. Set OE
to “0”, and BS1 to “0”. The EEPROM Data byte can now be read at DATA.
5. Set OE
to “1”.
Programming the
Fuse Low Bits
The algorithm for programming the Fuse Low bits is as follows (refer to “Programming the Flash”
on page 293 for details on Command and Data loading):
1. A: Load Command “0100 0000”.
2. C: Load Data Low Byte. Bit n = “0” programs and bit n = “1” erases the Fuse bit.
3. Set BS1 to “0” and BS2 to “0”.
4. Give WR
a negative pulse and wait for RDY/BSY to go high.
RDY/BSY
WR
OE
RESET +12V
PAGEL
BS2
0x11 ADDR. HIGH
DATA
ADDR. LOW DATA ADDR. LOW DATA XX
XA1
XA0
BS1
XTAL1
XX
AGB CEB C EL
K
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