ATmega8U2/16U2/32U2
Figure 25-4. Programming the EEPROM Waveforms
K
A
G
B
C
E
B
C
E
L
0x11
ADDR. HIGH
ADDR. LOW
DATA
ADDR. LOW
DATA
XX
XX
DATA
XA1
XA0
BS1
XTAL1
WR
RDY/BSY
RESET +12V
OE
PAGEL
BS2
25.7.6
Reading the Flash
The algorithm for reading the Flash memory is as follows (refer to “Programming the Flash” on
page 253 for details on Command and Address loading):
1. A: Load Command “0000 0010”.
2. H: Load Address Extended Byte (0x00- 0xFF).
3. G: Load Address High Byte (0x00 - 0xFF).
4. B: Load Address Low Byte (0x00 - 0xFF).
5. Set OE to “0”, and BS1 to “0”. The Flash word low byte can now be read at DATA.
6. Set BS to “1”. The Flash word high byte can now be read at DATA.
7. Set OE to “1”.
25.7.7
Reading the EEPROM
The algorithm for reading the EEPROM memory is as follows (refer to “Programming the Flash”
on page 253 for details on Command and Address loading):
1. A: Load Command “0000 0011”.
2. G: Load Address High Byte (0x00 - 0xFF).
3. B: Load Address Low Byte (0x00 - 0xFF).
4. Set OE to “0”, and BS1 to “0”. The EEPROM Data byte can now be read at DATA.
5. Set OE to “1”.
25.7.8
Programming the Fuse Low Bits
The algorithm for programming the Fuse Low bits is as follows (refer to “Programming the Flash”
on page 253 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. Give WR a negative pulse and wait for RDY/BSY to go high.
256
7799D–AVR–11/10
ATMEL [ ATMEL ]
