Hi, I have some doubts on the interfaces available on noc shell and axi wrapper. Based on the deep dive slides noc shell provides 3 bidirectional busses:
* Command & response Looking at the noc_shell code this should be indicated as control source. This bus seems to be able to send commands to other blocks. Is the command sink really usable to have a block send commands to other blocks? * Data packets This should just contain sample data in and out of the block * Settings bus This should be what noc shell code calls control sink and is basically an axi bus that is used to read and write registers. In axi_wrapper the settings bus is decoded to allow sending axi streaming packets to each configured busses through registers 129 and 130. This basically allows sending packets of configuration data to each configured bus over the AXI configuration busses. It is used in window block to send window data Axi wrapper also allows looping timestamp data or vice substituting it with user generated data. One thing I don't understand is for example that in the rfnoc getting started web page the gain sample uses register 128 which according to the deep dive ppt is supposed to be reserved for axi wrapper next destination, whereas the noc_shell_regs.v seems to indicate SR_NEXT_DST_SID is 6... it seems to me deep dive ppt is outdated and settings registers from 128 on can be feely used as long as they aren't used for configuration busses... correct? Another thing I think I understood is that the settings register space can be used for both reads and writes and provides a 32 bit data bus and has only 128 addresses left for user application of which 2*channels are used for configuration busses. This address space is separate from the user readback which provide another 256 x 64 bit possible readback registers which are completely separate from the settings register space.. while it makes sense it's not totally clear why an additional dedicated addressing space was needed for reading 64 bit back data and why for example there is no equivalent for writing. Thanks, Dario
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