254
AT90PWM216/316 [DATASHEET]
7710H–AVR–07/2013
Figure 23-2. Memory Sections
Note:
23.4
Boot Loader Lock Bits
If no Boot Loader capability is needed, the entire Flash is available for application code. The Boot Loader has two
separate sets of Boot Lock bits which can be set independently. This gives the user a unique flexibility to select dif-
ferent levels of protection.
The user can select:
To protect the entire Flash from a software update by the MCU.
To protect only the Boot Loader Flash section from a software update by the MCU.
To protect only the Application Flash section from a software update by the MCU.
Allow software update in the entire Flash.
See
Table 23-2 and
Table 23-3 for further details. The Boot Lock bits can be set in software and in Serial or Paral-
lel Programming mode, but they can be cleared by a Chip Erase command only. The general Write Lock (Lock Bit
mode 2) does not control the programming of the Flash memory by SPM instruction. Similarly, the general
Read/Write Lock (Lock Bit mode 1) does not control reading nor writing by LPM/SPM, if it is attempted.
0x0000
Flashend
Program Memory
BOOTSZ = '11'
Application Flash Section
Boot Loader Flash Section
Flashend
Program Memory
BOOTSZ = '10'
0x0000
Program Memory
BOOTSZ = '01'
Program Memory
BOOTSZ = '00'
Application Flash Section
Boot Loader Flash Section
0x0000
Flashend
Application Flash Section
Flashend
End RWW
Start NRWW
Application Flash Section
Boot Loader Flash Section
End RWW
Start NRWW
End RWW
Start NRWW
0x0000
End RWW, End Application
Start NRWW, Start Boot Loader
Application Flash Section
Read-While-Wr
ite
Section
No
Read-While-Wr
ite
Section
Read-While-Wr
ite
Section
No
Read-While-Wr
ite
Section
Read-While-Wr
ite
Section
No
Read-While-Wr
ite
Section
Read-While-Wr
ite
Section
No
Read-While-Wr
ite
Section
End Application
Start Boot Loader
End Application
Start Boot Loader
End Application
Start Boot Loader