Hey Jason,
You can send a command packet to another block via noc_shell's cmd_out
port. Command packets basically encapsulate a settings bus write. In
the payload of the command packet, the upper 32 bits are the settings
register address and the lower 32 bits are the data. Also, the block
will reply with a response packet, make sure to receive it (or just
leave ackin_tready set to 1'b1.)
There are a few things to be aware of though when manually sending out
command packets in a RFNoC block:
- This is a raw packet, so you will need to setup the header which
includes knowing the SID of the receiving block. That is easy if you
know which xbar port it is connected to: SID = {8'd0 (xbar ID), 4'd#
(xbar port), 4'd0 (block port)}. To find the xbar port, look at the
rfnoc_ce_auto_inst_<device>.v file and find the array index of the
receiving block. For X3x0 devices, xbar port = array index + 5.
- The host will be unaware of any changes you made. If that is an
issue, you could try implementing a readback register that the host
regularly polls.
- Sending many timed commands requires extra care. RFNoC blocks store
timed commands in a FIFO until they are executed. UHD tracks the FIFO
depth to prevent overflow, but noc_shell does not. You can control the
depth of the FIFO via noc_shell's CMD_FIFO_SIZE parameter.
Jonathon
On Tue, Jul 31, 2018 at 4:12 AM, Jason Matusiak via USRP-users
<usrp-users@lists.ettus.com> wrote:
> I am curious if it is possible to enable an RFNoC block from another RFNoC
> block? An example would be, turning on the siggen when another RFNoC block
> decides that it should run.
>
> I don't believe that I've seen this done anywhere, so I have a suspicion
> that there isn't a good way to get messages from one RFNoC to another
> without going through the host first.
>
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>
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