AT89C51ED2-RDTIM datasheet(101/137 Pages) ATMEL

101 / 137 page

101

AT89C51RD2/ED2

4235E–8051–04/04

Functional Description

Figure 42. 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 section “Bootloader Protocol”). This process translate serial communica-

tion 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

program 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 program-

ming 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 pur-

pose 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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