
520
42073A-MCU Wireless-02/13
ATmega2564/1284/644RFR2
Low: > 2 CPU clock cycles for fck < 12 MHz, 3 CPU clock cycles for fck >= 12 MHz;
High: > 2 CPU clock cycles for fck < 12 MHz, 3 CPU clock cycles for fck >= 12 MHz;
31.9.2 Serial Programming Algorithm
When writing serial data to the ATmega2564/1284/644RFR2, data is clocked on the
rising edge of SCK.
When reading data from the ATmega2564/1284/644RFR2, data is clocked on the falling
To program and verify the ATmega2564/1284/644RFR2 in the serial programming
mode, the following sequence is recommended (See four byte instruction formats in
1. Power-up sequence: Apply power between DEVDD and DVSS while RSTN and SCK
are set to “0”. In some systems, the programmer can not guarantee that SCK is held
low during power-up. In this case, RSTN must be given a positive pulse of at least
two CPU clock cycles duration after SCK has been set to “0”.
2. Wait for at least 20 ms and enable serial programming by sending the Programming
Enable serial instruction to pin PDI.
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 RSTN 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 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 Address Extended High Byte has been used to define the MSB of
the address. The address extended high byte with the address lines 23:16 is stored
until the command is re-issued, i.e., the command needs only be issued for the first
page, and when crossing the 64k word boundary. If polling (RDY/BSY
) is not used,
the user must wait at least tWD_FLASH before issuing the next page (see Table 31-17 on page 521). 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
521). 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 PDO. When reading the Flash
memory, use the instruction Load Address Extended High Byte to define the upper
address byte, which is not included in the Read Program Memory instruction. The
address extended high byte with the address lines 23:16 is stored until the command
is re-issued, i.e., the command needs only be issued for the first page, and when
crossing the 64k word boundary.
7. At the end of the programming session, RSTN can be set high to commence normal
operation.