Forget about I said with WDT, it doesn't work either.

Here is an update of my message:

I used FlashMagic and the ROM ISP to uptate the code in Philips P89C51RC2FA.
But have the following requirement: some external devices need to be initialised by uC at powerup, it also need to be the fact when reprogramming the device.
So I writed functions to replace the 'In System Programming'.
All the read fonctions are working very well. But not the ones for erasing the flash memory!
When I make a call to the ROM entry point, it dosent't return and do a reset.

If someone could help me, he will be welcome.


Here under is the asm code I use to errase the flash:

Save This Code

CSEG    AT 7000h
; ERASE BLOCK
ORL AUXR1,#20h	; ENBOOT bit determines whether the BOOTROM is enabled
or disabled
MOV R0,#11	; R0 = osc freq (integer)
MOV R1,#01h
MOV DPH,#0	;block code, block 0, 0k to 8k, 00H
MOV DPL,#0
LCALL PGM_MTP	; 0FFF0h
; It never returne here!?