Configuration File

The configuration file contains a list of parameters, which are used to configure the project. The parameters are described in the following table.

Table 1. Summary of Configuration File Options
Parameter	Description	Default	Required
PAGE_SIZE	Size of AVR Flash page in decimal bytes. This parameter is part dependent. See the data sheet.	N/A	Yes
KEY1	First part (128-bit) of the encryption key in hex. Should be 16 random bytes, with odd-parity bits inserted after every 8^th bit, making a total of 18 bytes.	None: No encryption	No, but strongly recommended
KEY2	Second part (64-bit) of the encryption key in hex. Should be eight random bytes, with odd-parity bits inserted after every 8^th bit, making a total of nine bytes. If omitted, AES128 will be used.	None: Use AES128	No, but recommended
KEY3	Third part (64-bit) of the encryption key in hex. Should be nine random bytes, with odd-parity bits inserted after every 8^th bit, making a total of nine bytes. If omitted AES128 or AES192 will be used.	None: Use AES128 or AES192	No, but recommended
INITIAL_VECTOR	Used for chaining cipher blocks. Should be 16 random bytes in hex.	0	No, but strongly recommended
SIGNATURE	Frame validation data in hex. This can be any four bytes, but it is recommended that the values are chosen at random.	0	No
ENABLE_CRC	Enable CRC checking: YES or NO. If enabled, the whole application section will be overwritten and the application must pass a CRC check before it is allowed to start.	No	No, but recommended
MEM_SIZE	Size of application section in target AVR (in decimal bytes).	N/A	Yes, if CRC is used

The configuration file can be given any valid file name. The name is later given as a parameter to the application that will create the project files. Below is a sample configuration file for the ATmega328PB. The KEY1 parameter is an example 128-bit key (hex 0123456789ABCDEF0123456789ABCDEF) with parity bits inserted.

PAGE_SIZE      = 128
MEM_SIZE       = 30720
CRC_ENABLE     = YES
KEY1           = EC38ECC4C11DBC16151A5E346A872AADAD36
INITIAL_VECTOR = F24D994D5DD3E9F1EEE897616C425028
SIGNATURE      = 89DBF334

Some of the parameters cannot be set without specific knowledge of the target AVR. The following table summarizes the features of some present AVR microcontrollers with bootloader functionality. For devices not present in this table, refer to the data sheet of the device.

Table 2. AVR Feature Summary
Feature	M8	M16	M162	M169	M32	M64	M128	M328PB
Flash Size, bytes	8192	16384	16384	16384	32768	65536	131072	32768
Flash Page size, bytes	64	128	128	128	128	256	256	128
Flash Pages	128	128	128	128	256	256	512	256
BLS (max.), bytes	2048	2048	2048	2048	4096	8192	8192	4096
BLS (max.) Pages	32	16	16	16	32	32	32	32
MEM_SIZE (min.), bytes	6144	14336	14336	14336	28672	57344	122880	28672
PAGE_SIZE, bytes	64	128	128	128	128	256	256	128