AT89C51ED2-RDTIM datasheet(114/137 Pages) ATMEL

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114

AT89C51RD2/ED2

4235E–8051–04/04

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 appli-

cation note:

C Flash Drivers for the AT89C51RD2/ED2

The API calls description and arguments are shown in Table 76.

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 come-

back in the application.

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

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 76. API Call Summary

Command

DPTR0

DPTR1

Returned Value

Command Effect

READ MANUF ID

00h

XXh

0000h

XXh

ACC = Manufacturer

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

Address of

byte to

program

Program one Data Byte in user Flash

XXh

Erase Software boot vector and boot status

byte. (SBV = FCh and BSB = FFh)

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