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Problem about the ioport keyword!

xiong4274
Prodigy 90 points
Other Parts Discussed in Thread: TMS320F28335

Hi,

    I want to use the ioport keyword to access to the XINTF Zone 7 space of the TMS320F28335.

The start address of Zone 7 is 0x20 0000 while the ioport type only should be char, short, int, or unsigned int.

So the compilation is failed and the error is " syntax error or ioport out of range"!

 I found that the direct address access without ioport keyword is available. What's the difference between the

access with ioport keyword and without it ?  

  • 0
    TI__Guru* 92680 points

    Xiong,

    Some devices have a special memory region called I/O space.  This region requires special opcodes to access it (for example in and out instructions) and thus you use the ioport keyword to tell C this is needed.

    On 28x devices, however, I/O space is not used.  All memory (including the flash and XINTF) is available in program and data space.   All peripheral registers are available in data space.  No special I/O opcodes are needed to access anything on the device.  

    Regards

    Lori

  • 0 in reply to Lori Heustess
    Prodigy 90 points

    Thanks!

    I understand. Only the access to the memory region mapped to I/O space needs the ioport keyword.