ATmega8U2/16U2/32U2
Figure 25-3. Programming the Flash Waveforms(1)
F
A
B
C
D
E
B
C
D
E
G
I
H
0x10
ADDR. LOW
DATA LOW
DATA HIGH
ADDR. LOW DATA LOW
DATA HIGH
ADDR. HIGH
ADDR. EXT.H
XX
XX
XX
DATA
XA1
XA0
BS1
BS2
XTAL1
WR
RDY/BSY
RESET +12V
OE
PAGEL
Note:
1. “XX” is don’t care. The letters refer to the programming description above.
25.7.5
Programming the EEPROM
The EEPROM is organized in pages, see Table 25-8 on page 249. When programming the
EEPROM, the program data is latched into a page buffer. This allows one page of data to be
programmed simultaneously. The programming algorithm for the EEPROM data memory is as
follows (refer to “Programming the Flash” on page 253 for details on Command, Address and
Data loading):
1. A: Load Command “0001 0001”.
2. G: Load Address High Byte (0x00 - 0xFF).
3. B: Load Address Low Byte (0x00 - 0xFF).
4. C: Load Data (0x00 - 0xFF).
5. E: Latch data (give PAGEL a positive pulse).
K: Repeat 3 through 5 until the entire buffer is filled.
L: Program EEPROM page
1. Set BS2, BS1 to “00”.
2. Give WR a negative pulse. This starts programming of the EEPROM page. RDY/BSY
goes low.
3. Wait until to RDY/BSY goes high before programming the next page (See Figure 25-4
for signal waveforms).
255
7799D–AVR–11/10
ATMEL [ ATMEL ]
