Rainbow Electronics ATmega161L - Manual (Page 127)

127
ATmega161(L)
1228C–AVR–08/02
t
WD_FLASH
before programming the next page. As a chip-erased device contains $FF in
all locations, programming of addresses that are meant to contain $FF can be skipped.
See Table 46 for t
WD_FLASH
value.
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 keep 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 46 for t
WD_EEPROM
value.
Figure 80. Serial Programming Waveforms
Table 46. Minimum Wait Delay before Writing the Next Flash or EEPROM Location
Symbol Minimum Wait Delay
t
WD_FLASH
14 ms
t
WD_EEPROM
3.4 ms
Table 47. Minimum Wait Delay after a Chip Erase Command
Symbol Minimum Wait Delay
t
WD_ERASE
28 ms
MSB
MSB
LSB
LSB
SERIAL CLOCK INPUT
PB7(SCK)
SERIAL DATA INPUT
PB5 (MOSI)
PB6 (MISO)
SAMPLE
SERIAL DATA OUTPUT