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This should be easy.....

Joseph Mingrone

I just started writing a C application for the Cygnal C8051F125 and am having difficulty setting/viewing the paged SFR's

Here's a simple example in C code:

SCON0=0x50;
SCON1=0x40;

Compiles fine, but when when I open the disassembly window, these 2 statements get translated to:

MOV SCON0(0x98),#0x50
MOV SCON0(0x98),#0x40

i.e., both statements modify SCON0. This is confirmed by opening the peripheral window and examining Serial port 1 and 2 --- SCON1 never changes (?????)

I understand the SFRs on the chip are spread over 5 pages, sharing common "base addresses" (0x98 in this case), but how do I access a specific page? And how do I view the different pages in the memory window?

This CAN'T be a bug, so what am I doing wrong?

Thanks,

Joe

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  • 0 in reply to Drew Davis

    So to put this to rest you are saying..

    1) I can't setup any peripheral on C8051F12x processors with "non-base page" SFR's in C code

    2) To set up any of these SFR's i'll need to do it in assembly, like:

    (save current SFR page#)

    MOV SFRPAGE, <SFR page number>
    MOV #<SFRREG>,<0xdd>

    (restore SFR page number)

    3) Ignore the peripheral dialog for this device and the one for the corresponding base page (because it gets confused by the write to the upper SFR).


    4) Probably alot of other work-arounds....

    I suppose I can do all that. My only beef is that the Keil site lists no such restrictions on these peripherals. In fact they say "The following on-chip peripherals are simulated by the Keil Software uVision Debugger" ..and goes on to list every peripheral except flash memory - misleading at the least.

    Buyer beware?

Reply
  • 0 in reply to Drew Davis

    So to put this to rest you are saying..

    1) I can't setup any peripheral on C8051F12x processors with "non-base page" SFR's in C code

    2) To set up any of these SFR's i'll need to do it in assembly, like:

    (save current SFR page#)

    MOV SFRPAGE, <SFR page number>
    MOV #<SFRREG>,<0xdd>

    (restore SFR page number)

    3) Ignore the peripheral dialog for this device and the one for the corresponding base page (because it gets confused by the write to the upper SFR).


    4) Probably alot of other work-arounds....

    I suppose I can do all that. My only beef is that the Keil site lists no such restrictions on these peripherals. In fact they say "The following on-chip peripherals are simulated by the Keil Software uVision Debugger" ..and goes on to list every peripheral except flash memory - misleading at the least.

    Buyer beware?

Children
  • 0 in reply to Joseph Mingrone

    I thought my previous answer to this question answered all these questions: http://www.keil.com/forum/docs/thread3024.asp

    Anyway, the simulation description for the Cygnal C8051F125 (http://www.keil.com/dd/chip/3474.htm) includes the following note:

    NOTE
    Simulation for this device is provided by the default peripheral simulation driver. Complete on-chip peripheral simulation is not available at this time.

    For each simulation DLL we create, there exists a default driver that is intended to be a catchall for those devices that are not explicitly simulated. This works better in some cases than in others.

    Maybe you guys can help us come up with the best text to use that clearly states that the default simulation driver is used (and that it may not match the device 100%). As far as I can tell, Cygnal parts have the greatest deviation from the default driver.

    Jon

  • 0 in reply to Joseph Mingrone

    You CAN set the registers in C code. You can set any registers, including the Page register, which is just another SFR. There is no need to use assembler, but also nothing wrong with using an assembler routine to push/pop the page before/after changing it.

  • 0 in reply to Jon Ward

    You can still access the sfr's from C, without using assembly. It'll just take you two statements.

    SFRBASE = 1;
SCON1 = 0x50;

    If that seems like too much trouble, or too likely to split the lines, a function or macro would solve the problem. If all the SFRs happen to be declared appropriately (and you could always change the reg.h file if they weren't), you might even get some mileage out of the token-pasting operator.

    #define PagedSfr(name,page)    SFRBASE = page, name##page

    That's off the top of my head, and untested, perhaps a bad idea since I don't use the comma operator a lot. But it looks like it'll work in two major contexts:

       val = PagedSfr(SCON, 1);
   PagedSfr(SCON, 1) = val;
   PagedSfr(SCON, 0) = val;

    Though it might be simpler and easier to have a read and a write macro. You also might prefer to return the SFR page register to its previous state, or a known state (0), after every write, to avoid possible confusion.

    None of that helps you with the simulator, of course.

  • 0 in reply to J Guy

    I would also like to nominate this thread for "Best Descriptive Title"