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Altera_Forum's avatar
Altera_Forum
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13 years ago

connection between processors through custom instructions: nothing works

hello everybody,

i'm trying to connect two processors trough custom instructions (ci).

Each processor has a ci which could respectively send and receive data to and from the other ci.

Before that i have verified that the custom instructions works well (i connect two blocks to each custom instruction; one sent data to ci and the other received data from ci ).

When i try to realize the connection between the two ci, i remarked that nothing walks. From signal tab i see that nothing is sent by the custom instructions.

i worked with a frequency of 50 MHz. i reduced it to 27 MHz but nothing changes.

what could be the origins of this problem?

thanks for your help

1 Reply

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    13 years ago

    I presume you are using 'multi cycle' custom instructions (possibly with a fixed cycle count of 1), rather than 'combinatorial' ones. Otherwise you don't have an 'enable' signal and clock.

    To transfer data you need some latch (or fifo) to hold the data written by one cpu before being read (at a later time) by the other. For real transfer you'll need some extra control signals for flow control (etc).

    Not sure which part isn't working ...