T89C51RD2-3CWC-L datasheet(51/86 Pages) ATMEL

51 / 86 page

Rev. F - 15 February, 2001

T89C51RD2

The bootloader and the In Application Programming (IAP) routines are located in the last kilobyte of the FLASH,

leaving 63k bytes available for the application with ISP.

8.4. FLASH registers and memory map

The T89C51RD2 FLASH memory uses several registers for his management:

• Flash control register is used to select the Flash memory spaces and launch the Flash programming sequence.

• Hardware registers can only be accessed through the parallel programming modes which are handled by the

parallel programmer.

• Software registers are in a special page of the FLASH memory which can be accessed through the API or with

the parallel programming modes. This page, called "Extra FLASH Memory", is not in the internal FLASH

program memory addressing space.

8.4.1. FLASH register

FCON (S:D1h)

FLASH control register

Reset Value = xxxx 0000b

Figure 18. FCON register

The Flash programming application note and API source code are available on request.

8.4.2. Hardware register

The only hardware register of the T89C51RD2 is called Hardware Security Byte (HSB). After full FLASH erasure,

the content of this byte is FFh; each bit is active at low level.

76543210

FPL3

FPL2

FPL1

FPL0

FPS

FMOD1

FMOD0

FBUSY

Bit Number

Bit Mnemonic

Description

7-4

FPL3:0

Programming Launch command bits

Write 5h followed by Ah to launch the programming.

FPS

FLASH Map Program Space

Clear to map the data space during MOVX

Set to map the FLASH space during MOVX (write) or MOVC (read) instructions (Write in the

column latches)

2-1

FMOD1:0

FLASH Mode

Select the addressed space

00: User (0000h-FFFFh)

01: XAF

10: Hardware byte

11: reserved

FBUSY

FLASH Busy

Set by hardware when programming is in progress.

Clear by hardware when programming is done.

Can not be cleared by software

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