Rainbow Electronics ATmega128L - Manual (Page 294)

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ATmega128(L)
2467B–09/01
ing the third byte of the Programming Enable instruction. Whether the echo is
correct or not, all 4 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.
4. The Flash is programmed one page at a time. 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 Program
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
129). Accessing the serial programming interface before the Flash write opera-
tion completes can result in incorrect programming.
5. 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 129). In a chip erased device, no $FFs 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
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 129 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