2010-03-16 11:14:32     Timeout for External But Interface

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2010-03-16 11:14:32     Timeout for External But Interface

Patrick Hotz (GERMANY)

Message: 87271   

 

Hi,

 

maybe this is not the best place to ask this, but this is a big problem for our project...

 

I have a Chip connected to the external bus interface fom the Blackfin BF537 (Data, Addr, ARE, AWE and ARDY).

This is running OK and the transfer from data to this chip is working..

 

But if the external chip chrashes, the blackfin freezes also because the ARDY is low and the blackfin is waiting until the universe collapse....

Is there any way to set a timeout for the ready-signal? Maybe i can set 1us and read after this timeout a flag in a error register??

 

Thanks,

 

Patrick

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2010-03-16 11:22:18     Timeout for External But Interface

Michael Hennerich (GERMANY)

Message: 87272    >Is there any way to set a timeout for the ready-signal?

 

No

 

> Maybe i can set 1us and read after this timeout a flag in a error register??

 

When ARDY is asserted - the current instruction fails to complete and your core freezes.

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2010-03-16 14:33:12     Re: Timeout for External But Interface

Robin Getz (UNITED STATES)

Message: 87282   

 

Michael:

 

I thought BnRDYEN controlled things.

 

Bank n ARDY enable

0 - Ignore ARDY for accesses to this memory bank

1 - After access time countdown, use state of ARDY to determine completion of access

 

 

If it is set to 1 - then things are as you say (nothing, including JTAG can break in) - otherwise -- it is ignored.

 

-Robin

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2010-03-16 16:19:49     Re: Timeout for External But Interface

Michael Hennerich (GERMANY)

Message: 87290    > Michael:

>

> I thought BnRDYEN controlled things.

 

Sure ARDY can be globally controlled (per ASYNC bank)

- but if the applications requires ARDY cycle extension - there is nothing you can do in case the external device permanently asserts ARDY.

Using some external logic - for example a 8-bit counter clocked by SCLKOUT, RESET by ARDY and the CARRY_OUT used to qualify ARDY might be a safeguard for buggy external peripherals.

 

-Michael

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2010-03-18 11:20:52     Re: Timeout for External But Interface

Patrick Hotz (GERMANY)

Message: 87406   

 

Hi,

 

thank you for the ideas with disable ARDY or use a external hardware...

I will try it on both ways and see what is better working for me.

 

Patrick

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