ATmega88PA Automotive Atmel Corporation, ATmega88PA Automotive Datasheet - Page 277

• Manufacturer Part Number: ATmega88PA Automotive
• Manufacturer: Atmel Corporation

27. Boot Loader Support – Read-While-Write Self-Programming
27.1
27.2
27.3
27.3.1
27.3.2
9223B–AVR–09/11
Features
Overview
Application and Boot Loader Flash Sections
Application Section
BLS – Boot Loader Section
The Boot Loader Support applies to Atmel
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Note:
In the Atmel ATmega88A/88PA/168A/168PA/328/328P the Boot Loader Support provides a
real Read-While-Write Self-Programming mechanism for downloading and uploading program
code by the MCU itself. This feature allows flexible application software updates controlled by
the MCU using a Flash-resident Boot Loader program. The Boot Loader program can use any
available data interface and associated protocol to read code and write (program) that code
into the Flash memory, or read the code from the program memory. The program code within
the Boot Loader section has the capability to write into the entire Flash, including the Boot
Loader memory. The Boot Loader can thus even modify itself, and it can also erase itself from
the code if the feature is not needed anymore. The size of the Boot Loader memory is configu-
rable with fuses and 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 different levels of protection.
The Flash memory is organized in two main sections, the Application section and the Boot
Loader section (see
BOOTSZ Fuses as shown in
can have different level of protection since they have different sets of Lock bits.
The Application section is the section of the Flash that is used for storing the application code.
The protection level for the Application section can be selected by the application Boot Lock
bits (Boot Lock bits 0), see
any Boot Loader code since the SPM instruction is disabled when executed from the Applica-
tion section.
While the Application section is used for storing the application code, the The Boot Loader
software must be located in the BLS since the SPM instruction can initiate a programming
when executing from the BLS only. The SPM instruction can access the entire Flash, including
the BLS itself. The protection level for the Boot Loader section can be selected by the Boot
Loader Lock bits (Boot Lock bits 1), see
Read-While-Write Self-Programming
Flexible Boot Memory Size
High Security (Separate Boot Lock Bits for a Flexible Protection)
Separate Fuse to Select Reset Vector
Optimized Page
Code Efficient Algorithm
Efficient Read-Modify-Write Support
Atmel ATmega48PA/88PA/168PA [Preliminary]
1. A page is a section in the Flash consisting of several bytes (see
used during programming. The page organization does not affect normal operation.
(1)
Size
Figure
Table 27-2 on page
27-2). The size of the different sections is configured by the
Table 27-7 on page 290
Table 27-3 on page
®
ATmega88A/88PA/168A/168PA/328/328P
281. The Application section can never store
and
Figure
281.
27-2. These two sections
Table 28-11 on page
299)
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