Datasheet

ATmega164A/PA/324A/PA/644A/PA/1284/P
 2018 Microchip Technology Inc. Data Sheet Complete DS40002070A-page 311
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 seven 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 address lines 15..8. Before issuing this command, make sure the instruction Load
Extended Address Byte has been used to define the MSB of the address. The extended address byte is
stored until the command is re-issued, that is, the command needs only be issued for the first page, and
when crossing the 64KWord boundary. If polling (
RDY/BSY) is not used, the user must wait at least
t
WD_FLASH
before issuing the next page. (See Table 27-16.) Accessing the serial programming interface
before the Flash write operation 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 27-16.) In a chip erased device, no 0xFFs 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. When reading the Flash memory, use the instruction Load
Extended Address Byte to define the upper address byte, which is not included in the Read Program
Memory instruction. The extended address byte is stored until the command is re-issued, that is, the
command needs only be issued for the first page, and when crossing the 64KWord boundary.
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.
Table 27-16. Minimum wait delay before writing the next flash or EEPROM location
Symbol Minimum wait delay
t
WD_FLASH
4.5ms
t
WD_EEPROM
3.6ms
t
WD_ERASE
9.0ms