megaAVR (JTAG) OCD memtypes

Table 1. megaAVR (JTAG) OCD memtypes
ID	Prog access	Debug access	Usage/rules
MEMTYPE_FLASH_PAGE	RW	-	Used for reading and writing FLASH pages in programming mode Writing it restricted to single full FLASH pages Reading is restricted to multiple full FLASH pages If access is attempted outside of programming mode, an error is returned ¹
MEMTYPE_EEPROM_PAGE	RW	-	Used to read and write EEPROM in programming mode Writing is restricted to single full pages Reading is restricted to multiple full pages If access is attempted outside of programming mode, an error is returned ²
MEMTYPE_FUSES	RW	-	Used to read and write FUSES in programming mode Up to 3 fuse bytes can be written/read in one operation. More than 3 results in an error.³ Up to address 0x02 can be accessed. Outside of this range results in an error.⁴ If access is attempted outside of programming mode, an error is returned ⁵
MEMTYPE_LOCKBITS	RW	-	Used to read and write LOCKBITS in programming mode Only a single lockbit byte is available to read, at address 0 Violating this results in an error ⁶ ⁷ If access is attempted outside of programming mode, an error is returned ⁸
MEMTYPE_SIGNATURE	R	-	Used to read the device SIGNATURE in programming mode Up to 3 signature bytes can be read in one operation. More than 3 results in an error.⁹ Up to address 0x02 can be accessed. Outside of this range results in an error.¹⁰ If access is attempted outside of programming mode, an error is returned ¹¹
MEMTYPE_OSCCAL	R	-	Used to read the device OSCCAL VALUES in programming mode Up to 4 bytes can be read in one operation. More than 4 results in an error.¹² Up to address 0x03 can be accessed. Outside of this range results in an error.¹³ If access is attempted outside of programming mode, an error is returned ¹⁴
MEMTYPE_SRAM	-	RW	Accesses SRAM and I/O space during debugging If used in programming mode, an error is returned ¹⁵ If a read attempts to read an area containing the OCDR register, an error is returned ¹⁶ A masked read must be used in this case Any number of bytes (within payload restrictions) can be written or read in one operation
MEMTYPE_EEPROM	-	RW	Used to read and write EEPROM during a debug session Any number of bytes can be written or read in one operation Uses monitor code heavily - may take some time to complete, depending proportionally upon the number of bytes being accessed
MEMTYPE_SPM	-	R	Used to read FLASH during a debug session If an odd number of bytes is requested, an error is returned ¹⁷ If a malaligned address is requested, an error is returned ¹⁸ Software breakpoints are filtered out
MEMTYPE_USER_SIGNATURE	RW	RW	Used to read/write the USER SIGNATURE in programming mode. Note: Applies to ATmegaxxxRFR2 devices only! Writing is restricted to single full FLASH pages Reading is restricted to multiple full FLASH pages