AT90PWM216-16SE ATMEL [ATMEL Corporation], AT90PWM216-16SE Datasheet - Page 267

• Manufacturer Part Number: AT90PWM216-16SE
• Description: 8-bit Microcontroller with 16K Bytes In-System Programmable flash
• Manufacturer: ATMEL [ATMEL Corporation]

24. Boot Loader Support – Read-While-Write Self-Programming
24.1
24.2
24.2.1
24.2.2
24.3
7710D–AVR–08/09
Boot Loader Features
Application and Boot Loader Flash Sections
Read-While-Write and No Read-While-Write Flash Sections
Application Section
BLS – Boot Loader Section
In AT90PWM216/316, the Boot Loader Support provides a real Read-While-Write Self-Program-
ming 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 configurable with fuses and the Boot Loader has two sepa-
rate sets of Boot Lock bits which can be set independently. This gives the user a unique
flexibility to select different levels of protection.
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Note:
The Flash memory is organized in two main sections, the Application section and the Boot
Loader section (see
BOOTSZ Fuses as shown in
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
Boot Loader code since the SPM instruction is disabled when executed from the Application
section.
While the Application section is used for storing the application code, the The Boot Loader soft-
ware 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
Whether the CPU supports Read-While-Write or if the CPU is halted during a Boot Loader soft-
ware update is dependent on which address that is being programmed. In addition to the two
sections that are configurable by the BOOTSZ Fuses as described above, the Flash is also
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
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 24-2 on page
Table 24-6 on page 279
24-2). The size of the different sections is configured by the
Table 24-3 on page
271. The Application section can never store any
271.
and
Figure
AT90PWM216/316
24-2. These two sections can
Table 25-11 on page
287)
267