ATMEGA644PV ATMEL [ATMEL Corporation], ATMEGA644PV Datasheet - Page 307

• Manufacturer Part Number: ATMEGA644PV
• Description: 8-bit Microcontroller with 16/32/64K Bytes In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

25.8.2
8011D–AVR–02/07
Serial Programming Algorithm
When writing serial data to the ATmega164P/324P/644P, data is clocked on the rising edge of
SCK.
When reading data from the ATmega164P/324P/644P, data is clocked on the falling edge of
SCK. See
To program and verify the ATmega164P/324P/644P in the serial programming mode, the follow-
ing sequence is recommended (See four byte instruction formats in
1. Power-up sequence:
2. Wait for at least 20 ms and enable serial programming by sending the Programming
3. The serial programming instructions will not work if the communication is out of synchro-
4. The Flash is programmed one page at a time. The memory page is loaded one byte at a
5. The EEPROM array is programmed one byte at a time by supplying the address and data
6. Any memory location can be verified by using the Read instruction which returns the con-
7. At the end of the programming session, RESET can be set high to commence normal
8. Power-off sequence (if needed):
Apply power between V
tems, the programmer can not guarantee that SCK is held low during power-up. In this
case, RESET must be given a positive pulse of at least two CPU clock cycles duration
after SCK has been set to “0”.
Enable serial instruction to pin MOSI.
nization. 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.
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 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, i.e., the command needs only be issued for
the first page, and when crossing the 64KWord boundary. If polling (
used, the user must wait at least t
16.) Accessing the serial programming interface before the Flash write operation com-
pletes can result in incorrect programming.
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
device, no 0xFFs in the data file(s) need to be programmed.
tent 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, i.e., the command needs only be issued for the
first page, and when crossing the 64KWord boundary.
operation.
Set RESET to “1”.
Turn V
Figure 25-12
CC
WD_EEPROM
power off.
before issuing the next byte. (See
for timing details.
CC
and GND while RESET and SCK are set to “0”. In some sys-
WD_FLASH
before issuing the next page. (See
ATmega164P/324P/644P
Table
25-16.) In a chip erased
Table
RDY/BSY
25-17):
) is not
Table 25-
307