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Example of Custom Instruction with External Interface

JSRT
Beginner
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Hello,

 

I'm looking for an example showing how to write and use an Nios2 CI with a external interface (as described in Sec. 2.1.5 of the Nios2 Custom Instruction Guide). 

 

I've already implemented simple combinational CIs. 

 

From what I've understood, CI with EI can access external data (as opposed to the 2x32bits arguments on their input ports) using a "conduit". I've no experience with such components and could find the relevant documentation.

 

Basically, what i'd like to do is to write CIs processing arrays, using the __builtin_custom_pnpp function interface on the Nios side, i.e. by writing the contents of the array in memory (on chip memory will be ok for now), having the CI process it and return the address of the result (either the same or another one, passed as the second arg. for ex).

Any help or advice on how to do this would be greatly appreciated

 

Jocelyn

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BoonBengT_Intel
Moderator
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Hi @JSRT,

 

Thank you for posting in Intel community forum, hope this message find you well and apologies for the delayed in response.
Per my understanding, the conduits are basically used for signals grouping, example bunch of control registers with the SPI interface will be group and called spi. (i.e. you should see it in the hw.tcl files)

 

As for the CI that are processing arrays, here would be a good example to start with.
Please do let us know if this helps to clarify your doubts.

 

Best Wishes
BB

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BoonBengT_Intel
Moderator
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Hi @JSRT,

 

Greetings, unfortunately as we do not receive any further clarification on what is provided. Hence thread will now be transitioned to community support where community users will further help you with doubts in this thread. For new queries, please feel free to open a new thread and we will be right with you. Pleasure having you here.

 

Best Wishes
BB

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