Datasheet
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 R1 A 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.