at89c5131a ATMEL Corporation, at89c5131a Datasheet - Page 24

• Manufacturer Part Number: at89c5131a
• Description: Usb Microcontrollers
• Manufacturer: ATMEL Corporation

In-Application
Programming/Self
Programming
API Call
Process
Constraints
24
AT89C5131A USB Bootloader
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 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
package:
C Flash Drivers for the AT89C5131A for Keil
The flash_api routines on the package work only with the USB bootloader.
The flash_api routines are listed in APPENDIX-B.
The application selects an API by setting the 4 variables available when the flash_api
library is linked to the application.
These four variables are located in RAM at fixed address:
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•
•
•
All calls are made through a common interface “USER_CALL” at the address FFC0h.
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.
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.
For more information regarding the Flash writing time see the AT89C5131A datasheet.
api_command: 1Ch
api_value: 1Dh
api_dph: 1Eh
api_dpl: 1Fh
®
Compilers
4287C–USB–11/04