AT89C51ED2-RDTUM datasheet(112/137 Pages) ATMEL

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112

4235K–8051–05/08

AT89C51RD2/ED2

24.10 API Call Description

The IAP allows to reprogram a microcontroller on-chip Flash memory without removing it from

the system and while the embedded application is running.

The user application can call some Application Programming Interface (API) routines allowing

IAP. These API are executed by the bootloader.

To call the corresponding API, the user must use a set of Flash_api routines which can be linked

with the application.

Example of Flash_api routines are available on the Atmel web site on the software application

note:

C Flash Drivers for the AT89C51RD2/ED2

The API calls description and arguments are shown in Table 24-10.

24.10.1

Process

The application selects an API by setting R1, ACC, DPTR0 and DPTR1 registers.

All calls are made through a common interface “USER_CALL” at the address FFF0h.

The jump at the USER_CALL must be done by LCALL instruction to be able to comeback in the

application.

Before jump at the USER_CALL, the bit ENBOOT in AUXR1 register must be set.

24.10.2

Constraints

The interrupts are not disabled by the bootloader.

Interrupts must be disabled by user prior to jump to the USER_CALL, then re-enabled when

returning.

Interrupts must also be disabled before accessing EEPROM Data then re-enabled after.

The user must take care of hardware watchdog before launching a Flash operation.

Table 24-10. API Call Summary

Command

DPTR0

DPTR1

Returned Value

Command Effect

READ MANUF ID

00h

XXh

0000h

XXh

ACC = Manufacturer Id

Read Manufacturer identifier

READ DEVICE ID1

00h

XXh

0001h

XXh

ACC = Device Id 1

Read Device identifier 1

READ DEVICE ID2

00h

XXh

0002h

XXh

ACC = Device Id 2

Read Device identifier 2

READ DEVICE ID3

00h

XXh

0003h

XXh

ACC = Device Id 3

Read Device identifier 3

ERASE BLOCK

01h

XXh

DPH = 00h

00h

ACC = DPH

Erase block 0

DPH = 20h

Erase block 1

DPH = 40h

Erase block 2

DPH = 80h

Erase block 3

DPH = C0h

Erase block 4

PROGRAM DATA BYTE

02h

Vaue to write

Address of

byte to

program

XXh

ACC = 0: DONE

Program up one data byte in the on-chip

flash memory.

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