ATMEga64L ATMEL Corporation, ATMEga64L Datasheet - Page 309

• Manufacturer Part Number: ATMEga64L
• Description: 8-bit AVR Microcontroller with 64K Bytes In-System Programmable Flash
• Manufacturer: ATMEL Corporation

Data Polling EEPROM
2490G–AVR–03/04
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 deter-
mine 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-programmed 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
t
Table 129. Minimum Wait Delay before Writing the Next Flash or EEPROM Location
Note:
Figure 148. SPI Serial Programming Waveforms
WD_EEPROM
Symbol
t
t
t
t
WD_FUSE
WD_FLASH
WD_EEPROM
WD_ERASE
SERIAL DATA OUTPUT
SERIAL CLOCK INPUT
SERIAL DATA INPUT
1. Flash write: per page
(1)
value.
SAMPLE
(MOSI)
(MISO)
(SCK)
WD_EEPROM
MSB
MSB
before programming the next byte. See Table 129 for
Minimum Wait Delay
4.5 ms
4.5 ms
9.0 ms
9.0 ms
ATmega64(L)
LSB
LSB
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