AT89C51AC2 datasheet(47/121 Pages) ATMEL

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A/T89C51AC2

4127G–8051–05/06

In-System

Programming (ISP)

With the implementation of the User Space (FM0) and the Boot Space (FM1) in Flash

technology the A/T89C51AC2 allows the system engineer the development of applica-

tions with a very high level of flexibility. This flexibility is based on the possibility to alter

the customer program at any stages of a product’s life:

•

Before mounting the chip on the PCB, FM0 Flash can be programmed with the

application code. FM1 is always preprogrammed by Atmel with a bootloader (UART

bootloader).(1)

•

Once the chip is mounted on the PCB, it can be programmed by serial mode via the

UART.

Note:

1. The user can also program his own bootloader in FM1.

This In-System-Programming (ISP) allows code modification over the total lifetime of the

product.

Besides the default Boot loader Atmel provide to the customer also all the needed Appli-

cation-Programming-Interfaces (API) which are needed for the ISP. The API are located

also in the Boot memory.

This allow the customer to have a full use of the 32 KB user memory.

Flash Programming and

Erasure

There are three methods of programming the Flash memory:

•

The Atmel bootloader located in FM1 is activated by the application. Low level API

routines (located in FM1) will be used to program FM0. The interface used for serial

downloading to FM0 is the UART. API can be called also by the user’s bootloader

located in FM0 at [SBV]00h.

•

A further method exists in activating the Atmel boot loader by hardware activation.

See Section “Hardware Security Byte”.

•

The FM0 can be programmed also by the parallel mode using a programmer.

Figure 25. Flash Memory Mapping

F800h

7FFFh

32 KB

Flash memory

2 KB IAP

bootloader

FM0

FM1

Custom

Boot Loader

[SBV]00h

FFFFh

FM1 mapped between F800h and FFFFh

when API called

0000h

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