Hi, I'm trying to access SFR memory using the hexa address of the SFR and using only "C" instructions. Since SFR memory is accessed by direct addressing mode, like the first 128 bytes of internal RAM, I tried to use the following instruction :
* ((unsigned char data *) 0xA8) = 0x1;
MOV R0,#0A8H MOV @R0,#01H
* ((unsigned char idata *) 0xA8) = 0x1;
The processor has only 1 set of registers; you can't just create a whole new set of "local" registers within a function! Sure but I want to name an SFR with a specific name within the local scope of a function. As you do with other parameters. And it appears that sfr can't be a parameter of a function. As I mentionned before, the SFR register to modify is unknown at compile time. I receive the address of the SFR in an unsigned char variable and don't know how to modify the corresponding SFR register value !!! So how can I do ? It seems that I have to modify the architecture of my software .... Arnaud
Sure but I want to name an SFR with a specific name within the local scope of a function. As you do with other parameters. And it appears that sfr can't be a parameter of a function. No! SFR's cannot be parameters. Parameters are pushed onto the stack or placed in fixed locations in regular memory - you cannot do this with registers. Please stop attempting to do this - these are not memory mapped registers like external device registers. As I mentionned before, the SFR register to modify is unknown at compile time. C51 doesn't know about any SFR's at compile time. By including reg51.h you define them. Give me the address and description of you mystery SFR and I'll show you how to access it. For that matter, what chip are you using? - Mark