Datasheet

2. Wait for at least 20ms and enable serial programming by sending the Programming Enable serial
instruction to pin MOSI.
3. The serial programming instructions will not work if the communication is out of synchronization.
When in sync. the second byte (0x53), 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 0x53 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 6 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 a given address. The Program Memory Page is stored by loading the Write
Program Memory Page instruction with the 8 MSB of the address. If polling is not used, the user
must wait at least t
WD_FLASH
before issuing the next page.
5. Note: If other commands than polling (read) are applied before any write operation (FLASH,
EEPROM, Lock Bits, Fuses) is completed, it may result in incorrect programming.
6. 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. In a chip erased device, no 0xFFs in the data file(s) need to be programmed.
7. Any memory location can be verified by using the Read instruction which returns the content at the
selected address at serial output MISO.
8. At the end of the programming session, RESET can be set high to commence normal operation.
9. Power-off sequence (if needed):
Set RESET to “1”.
Turn V
CC
power off.
29.9.2. 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 0xFF. 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 0xFF, 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 0xFF in all
locations, programming of addresses that are meant to contain 0xFF, can be skipped. See table in next
section for t
WD_FLASH
value.
29.9.3. 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 0xFF. 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 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 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
WD_EEPROM
before
programming the next byte. See table below for t
WD_EEPROM
value.
Atmel ATmega32A [DATASHEET]
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