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HPI problem with C6211

Started by Rastko Selmic February 9, 2001

Hi, I have a problem with HPI in C6211. I can write and read to and from
HPIC and HPIA. But I cannot have reliable read and write to HPID.

The only way I can do something is the following: HPIA write 0x2000
HPID++ write 0x12345678

HPIA write 0x1FFC
HPID++ read (returns something)
HPID++ read (returns 0x12345678)

The only thing that I have working is HPID autoincrement access, and even
then I need to have one extra read from the address before original. Have
you seen something like that?

Any comment about this?

Thank you. Rastko Selmic
Signalogic, Inc.





Hi,

It is correct becuase the way HPI C6XXX work is that it always prefetch
the next value using EDMA. For example if you want to read 0x1000, you
have to write to HPIA 0x0FFF to tell the EDMA to prefetch value at
0x1000. A better throughput will be achieved by this method in
autoincrement mode. I bet if you can read address 0x0000. :-)

It only happens for read, not write access.

One thing you can do is checking the RDY line before you read HPID again.

It happened the same for me and nonautoincrement doesn't work either.It is
documented in TI C6211 bug list as I recalled.

Cheers!

Duy K Do On Thu, 8 Feb 2001, Rastko Selmic wrote:

>
> Hi, > I have a problem with HPI in C6211. I can write and read to and from
> HPIC and HPIA. But I cannot have reliable read and write to HPID.
>
> The only way I can do something is the following: > HPIA write 0x2000
> HPID++ write 0x12345678
>
> HPIA write 0x1FFC
> HPID++ read (returns something)
> HPID++ read (returns 0x12345678)
>
> The only thing that I have working is HPID autoincrement access, and even
> then I need to have one extra read from the address before original. Have
> you seen something like that?
>
> Any comment about this?
>
> Thank you. > Rastko Selmic
> Signalogic, Inc. >
>
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