Rainbow Electronics ATmega32L - Manual (Page 270)

270
ATmega32(L)
2503C–AVR–10/02
Data Polling Flash When a page is being programmed into the Flash, reading an address location within
the page being programmed will give the value $FF. At the time the device is ready for a
new page, the programmed value will read correctly. This is used to determine when the
next page can be written. Note that the entire page is written simultaneously and any
address within the page can be used for polling. Data polling of the Flash will not work
for the value $FF, so when programming this value, the user will have to wait for at least
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 115 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 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 re-programmed 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 115 for t
WD_EEPROM
value.
Figure 137. SPI Serial Programming Waveforms
Table 115. 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