273
ATmega165A/PA/325A/PA/3250A/PA/645A/P/6450A/P [DATASHEET]
8285E–AVR–02/2013
used, the user must wait at least t
WD_FLASH before issuing the next page. (See Table 27-15.) Accessing the serial programming interface before the Flash write operation completes can result in incorrect
programming.
5.
A: The EEPROM array is programmed one byte at a time by supplying the address and data together with
the appropriate Write instruction. An EEPROM memory location is first automatically erased before new
data is written. If polling (RDY/BSY) is not used, the user must wait at least t
WD_EEPROM before issuing the
next byte (See
Table 27-15). In a chip erased device, no 0xFFs in the data file(s) need to be programmed.
B: The EEPROM array is programmed one page at a time. The Memory page is loaded one byte at a time
by supplying the 2 LSB of the address and data together with the Load EEPROM Memory Page instruction.
The EEPROM Memory Page is stored by loading the Write EEPROM Memory Page Instruction with the 4
MSB of the address. When using EEPROM page access only byte locations loaded with the Load
EEPROM Memory Page instruction is altered. The remaining locations remain unchanged. If polling
(RDY/BSY) is not used, the user must wait at least t
WD_EEPROM before issuing the next page (See Table 27- 15). In a chip erased device, no 0xFF in the data file(s) need to be programmed.
6.
Any memory location can be verified by using the Read instruction which returns the content at the selected
address at serial output MISO.
7.
At the end of the programming session, RESET can be set high to commence normal operation.
8.
Power-off sequence (if needed):
Set RESET to “1”.
Turn V
CC power off
Figure 27-11. Serial Programming waveforms.
Table 27-15. Minimum Wait Delay before writing the next Flash or EEPROM location.
Symbol
Minimum Wait Delay
tWD_FUSE
4.5ms
t
WD_FLASH
4.5ms
tWD_EEPROM
3.6ms
t
WD_ERASE
9.0ms
MSB
LSB
SERIAL CLOCK INPUT
(SCK)
SERIAL DATA INPUT
(MOSI)
(MISO)
SAMPLE
SERIAL DATA OUTPUT