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TMS320F280049C: C2000 compiler does not allow access adress of bp_32 variable in struct

Oliver Mihatsch
Prodigy 40 points
Part Number: TMS320F280049C
Other Parts Discussed in Thread: C2000WARE

Tool/software:

Hi,

I have problems accessing the addres of variables which are marked with the byte_peripheral attribute inside a struct.

This part compiles without issues:

typedef unsigned long bp_32 __attribute__((byte_peripheral));

bp_32 var = 1;
bp_32 *varPtr = &var;  // points to var

But if I encapsulate the variable in a struct, this does not work anymore:

struct {
    uint32_t val1;
    bp_32 val2;
} aStruct;

bp_32 *structVal1Ptr = &aStruct.val1;  // works fine
bp_32 *structVal2Ptr = &aStruct.val2;  // fails

The error message I'm getting in the last line is "Illegal use of intrinsic: __byte_peripheral_32" which is also a bit strange since I'm using the attribute. Guess that the compiler is just doing some kind of search/replace of the attribute.

This is quite in my way as I sometimes want to access the address of some registers which in this case does not work if they are marked with byte_peripheral.
Here is an example which also fails:

volatile bp_32 *perRegPtr = &CanbRegs.CAN_IF3UPD;

I'm using version 22.6.1 LTS from the latest C2000 Ware version 5.02.00.00.

Do you have a tip how I can get this working?

Thanks a lot and best regards,
Oliver

  • 0
    TI__Guru**** 244710 points

    Unfortunately, this ...

    Oliver Mihatsch said:
    accessing the addres of variables which are marked with the byte_peripheral attribute inside a struct.

    ... is not supported.  

    To get a better idea of how byte peripheral access is typically used, I suggest you view the examples in C2000Ware which use it.  I am not familiar with C2000Ware, so I will notify the C2000Ware experts about this thread.

    Thanks and regards,

    -George

  • 0 in reply to George Mock
    TI__Mastermind 34705 points

    Hi,

    You can refer to the drivers provided within C2000Ware for the byte peripherals like LIN. 

    The macro HWREG_BP is used to write to such registers.

    Best Regards

    Siddharth

  • 0 in reply to George Mock
    Prodigy 40 points

    Thanks for the fast response and the different alternatives.

    Yes, one option is to use the HWREG_BP to access registers:

    HWREG_BP(CANB_BASE + CAN_O_IF3UPD);

    But this is not really what I need. What I want is a pointer, in this case, to CANB_BASE + CAN_O_IF3UPD, which is just a number, so this is identical with:

    bp_32 *ptr = (bp_32 *)(CANB_BASE + CAN_O_IF3UPD);  // works
    bp_32     *ptr = (bp_32 *)0x4A160; // works too

    But repeating CANB_BASE + CAN_O_IF3UPD is painful, clutters the code and adds more dependencies when the struct already knows the address.

    Another workaround is to add another layer to the struct:

    struct {
        union { bp_32 val2; } un2;
    } aStruct;
    bp_32 *structVal2Ptr = (bp_32 *)&aStruct.un2;  // works

    But again, this is not nice, as I have to modify the TI structs/headers for this and it makes the code harder to read.

    George Mock said:
    ... is not supported.  

    Is it maybe possible that you forward this request to the compiler team?
    Perhaps it is just a small change in the compiler and it would make the usage of this register struct more efficient and easy.

    Thanks a lot and best regards,
    Oliver

  • 0 in reply to Oliver Mihatsch
    TI__Guru**** 244710 points

    I filed a request for this feature to be added to the compiler.  Unfortunately, there is a problem with the part of the system that makes such requests visible to customers.  So I am unable to give you a link.  The internal ID for the request is CODEGEN-12564.

    Please do not think that filing the request means it gets implemented.  It has to be approved, scheduled, etc. 

    Thanks and regards,

    -George

  • 0 in reply to George Mock
    TI__Guru**** 244710 points
    George Mock said:
    Unfortunately, there is a problem with the part of the system that makes such requests visible to customers. 

    Unfortunately, this problem has not been resolved.  I remain unable to get you a link.

    Thanks and regards,

    -George

  • +1 in reply to George Mock
    TI__Guru**** 244710 points

    The entry EXT_EP-11796 has been filed.  You are welcome to follow it with that link.  Thank you for your patience.

    Thanks and regards,

    -George

  • 0 in reply to George Mock
    Prodigy 40 points
    George Mock said:

    The internal ID for the request is CODEGEN-12564.

    Please do not think that filing the request means it gets implemented.  It has to be approved, scheduled, etc. 

    Understood and thanks a lot!

    Best regards,
    Oliver