Basic questions about CPU and peripheral control registers

Xinwang Zhang

Hi guys,

I just have couple of basic questions about the control registers.

1. peripheral control registers are addressed by "port address". Is "port address" included in the big memory map (the one with DARAM, SARAM, EMIF and so on)?

2. How to directly access the control register with C code if the port address is know? Like DRR10 of MCBSP, its port address is 0x2800. How to directly write and read this register with C code? The reason I am asking it is because I had a lot of problems when I was using CSL.

3. Do CPU registers locate in MMR section in DARAM?

Thanks.

over 14 years ago

0 Peter Chung over 14 years ago

TI__Expert 8065 points

Xinwang,

I/O registers are located in I/O space. To access I/O registers directly, do the following:

#define DRR10 *(ioport volatile unsigned *)0x2800

DRR10 = 0x0001 (writing 0x0001 to the I/O register 0x2800)

variable = DRR10 (reading the I/O register 0x2800)

MMR is allocated in 0x0 ~ 0xC0 (byte address). You can access MMR registers as the way you access DARAM.

Regards,

Peter Chung

0 Xinwang Zhang over 14 years ago in reply to Peter Chung

Prodigy 225 points

Thanks Peter.

How about the third question?

CPU registers? Do they locate in MMR or I/O space?

Thanks again for your reply!

0 Peter Chung over 14 years ago in reply to Xinwang Zhang

TI__Expert 8065 points

Yes, CPU registers are in MMR.

See details on CPU registers in the CPU reference guide:

http://focus.ti.com/lit/ug/swpu073e/swpu073e.pdf

Thanks,

Peter Chung

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Basic questions about CPU and peripheral control registers