Rainbow Electronics ATmega8515L - Manual (Page 191)

191
ATmega8515(L)
2512A–AVR–04/02
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 $FF. At the time the device is
ready for a new byte, the programmed value will read correctly. This is used to deter-
mine when the next byte can be written. This will not work for the value $FF, but the user
should have the following in mind: As a chip erased device contains $FF in all locations,
programming of addresses that are meant to contain $FF, can be skipped. This does
not apply if the EEPROM is reprogrammed without chip-erasing the device. In this case,
data polling cannot be used for the value $FF, and the user will have to wait at least
t
WD_EEPROM
before programming the next byte. See Table 93 for t
WD_EEPROM
value.
Figure 84. Serial Programming Waveforms
Table 93. Minimum Wait Delay Before Writing the Next Flash or EEPROM Location
Symbol Minimum Wait Delay
t
WD_FLASH
4.5 ms
t
WD_EEPROM
9.0 ms
t
WD_ERASE
9.0 ms
MSB
MSB
LSB
LSB
SERIAL CLOCK INPUT
(SCK)
SERIAL DATA INPUT
(MOSI)
(MISO)
SAMPLE
SERIAL DATA OUTPUT