ATMEGA8_14 Datasheet, PDF (232/331 Pages) ATMEL Corporation – High-performance, Low-power Atmel

ATmega8(L)
Data Polling EEPROM
When a new byte has been written and is being programmed into EEPROM, reading the
address location being programmed will give the value 0xFF. At the time the device is ready for
a new byte, the programmed value will read correctly. This is used to determine when the next
byte can be written. This will not work for the value 0xFF, but the user should have the following
in mind: As a chip-erased device contains 0xFF in all locations, programming of addresses that
are meant to contain 0xFF, can be skipped. This does not apply if the EEPROM is Re-pro-
grammed without chip-erasing the device. In this case, data polling cannot be used for the value
0xFF, and the user will have to wait at least t_{WD_EEPROM} before programming the next byte. See
Table 97 for t_{WD_EEPROM} value.
Table 97. Minimum Wait Delay Before Writing the Next Flash or EEPROM Location
Symbol
Minimum Wait Delay
t_{WD_FUSE}
t_{WD_FLASH}
t_{WD_EEPROM}
t_{WD_ERASE}
4.5ms
4.5ms
9.0ms
9.0ms
Figure 113. Serial Programming Waveforms
SERIAL DATA INPUT
MSB
LSB
(MOSI)
SERIAL DATA OUTPUT
MSB
LSB
(MISO)
SERIAL CLOCK INPUT
(SCK)
SAMPLE
2486AA–AVR–02/2013
232