ATmega128 datasheet(302/386 Pages) ATMEL

302 / 386 page

302

2467S–AVR–07/09

ATmega128

The SPI Serial Programming instructions will not work if the communication is out of syn-

chronization. When in sync. the second byte ($53), will echo back when issuing the third

byte of the Programming Enable instruction. Whether the echo is correct or not, all FOUR

bytes of the instruction must be transmitted. If the $53 did not echo back, give RESET a

positive pulse and issue a new Programming Enable command.

The Flash is programmed one page at a time. The page size is found in Table 124 on

page 292. The memory page is loaded one byte at a time by supplying the 7 LSB of the

address and data together with the Load Program Memory Page instruction. To ensure

correct loading of the page, the data low byte must be loaded before data high byte is

applied for given address. The Program Memory Page is stored by loading the Write Pro-

gram Memory Page instruction with the 9 MSB of the address. If polling is not used, the

user must wait at least t

WD_FLASH before issuing the next page. (See Table 128).

Note: If other commands than polling (read) are applied before any write operation (Flash,

EEPROM, Lock bits, Fuses) is completed, may result in incorrect programming.

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 is not used, the user must wait

at least t

WD_EEPROM before issuing the next byte. (See Table 128). In a chip erased device,

no $FFs in the data file(s) need to be programmed.

Any memory location can be verified by using the Read instruction which returns the con-

tent at the selected address at serial output MISO.

At the end of the programming session, RESET can be set high to commence normal

operation.

Power-off sequence (if needed):

Set RESET to “1”.

Turn V

CC power off.

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 writ-

ten. 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 128 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 determine 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 128

for t

WD_EEPROM value.

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