AT89C51ED2-RDTUM datasheet(99/137 Pages) ATMEL

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4235K–8051–05/08

AT89C51RD2/ED2

24.6.3

Functional Description

Figure 24-3. Bootloader Functional Description

On the above diagram, the on-chip bootloader processes are:

• ISP Communication Management

The purpose of this process is to manage the communication and its protocol between the on-

chip bootloader and a external device. The on-chip ROM implements a serial protocol (see sec-

tion “Bootloader Protocol”). This process translate serial communication frame (UART) into

Flash memory access (read, write, erase, etc.).

• User Call Management

Several Application Program Interface (API) calls are available for use by an application pro-

gram to permit selective erasing and programming of Flash pages. All calls are made through a

common interface (API calls), included in the ROM bootloader. The programming functions are

selected by setting up the microcontroller’s registers before making a call to a common entry

point (0xFFF0). Results are returned in the registers. The purpose on this process is to translate

the registers values into internal Flash Memory Management.

• Flash Memory Management

This process manages low level access to Flash memory (performs read and write access).

ISP Communication

Management

User

Application

Specific Protocol

Communication

Management

Flash

Memory

External Host with

Flash Memory

User Call

Management (API)

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