Hi! I use a T89C51CC01 from Atmel WM, I would like to use the dual dptr feature on my program. When I run the Debugger, i can't switch the DPTR. In the µC manual, it says that we must set the DPS bit of the AUXR1 register. I do this just before writing on the DPTR. When i set this bit and write just after on the DPTR register, the debugger show me that i write on the first DPTR and not in the second ? Does anyone konw why ?
save_table_eeprom: MOV A,EECON ANL A,#01H CJNE A,#00,save_table_eeprom ;Test si l'EEPROM n'est pas occupé ;Début de la programmation MOV EECON,#02H ORL AUXR,#020H MOV DPTR,#0081H MOV AUXR1,#01H MOV DPTR,#01C8H ;here it's my problem! MOVX @DPTR,A ;I rite on the bad DPTR ;Lancement du cycle d'écriture en EEPROM MOV EECON,#054H MOV EECON,#0A4H RET
C51 only ever uses the extra DPTR(s) in a limited set of library functions (memcpy, memmove, memcmp, strcpy, and strcmp), and you have to specifically enable that usage with a command-line option (or 'Use Multiple DPTR Registers' in the uVision Target Options). See the manual. You won't find C51 using multiple DPTRs in your own application code.