On Mon, 10 Aug 2020 10:23:40 -0700 (PDT), in
gmane.comp.hardware.beagleboard.user Peter Gaskell
<[email protected]> wrote:
>The Beaglebone creates its default SoftAP and connects to a WiFi router
>that has internet. By default, computers connecting to the SoftAP get the
>internet forwarded to them so both the laptop and the RPi can connect to
>the internet and I can ssh and remote desktop into the RPi from the laptop
>and ssh into the Beaglebone as well. All three appear on the same LAN
>(192.168.8.0) and all the LCM traffic is visible on the network.
>
Personally, to reduce interference I'd have all the devices connect to
the router... If I understand your description, you have the BBbl running
as an access point for other WiFi clients, and also connecting to the
router -- so every WiFi packet it receives from a client has to be resent
to the router. But...
>The problem I have is this. I would rather have the network connection
>between the Pi and BBBlue be over USB so there is higher bandwidth/lower
>latency connection between them because ultimately the largest share of
>data is going to be produced on the Pi (video / LIDAR messages / maps
>etc.), not the Beaglebone and I would like to be able to decode it on the
>laptop with as little latency as possible.
... I wouldn't even use WiFi between the R-Pi and the BBbl. While the BBx
USB client port does set up a USB network gadget (rndis on 192.168.7.x), I
don't know what it would take to have an R-Pi set up a matching USB gadget
on its host port (plug them together and see if a new network device
appears on the R-Pi?).
Simpler might be to use a USB<>Ethernet adapter on the BBbl, and a
short length of CAT-5/6 cable to connect to the R-Pi. Since I doubt either
machine is running a DHCPd, you'd have to manually configure the
hostname/IP #s to make a two-node network.
Once the two nodes are talking, you'd have to configure the BBbl to use
the R-Pi as the gateway, and configure the R-Pi to route traffic from the
BBbl port to the WiFi port, which is connected to your router. You'd have
the laptop connect to the router also -- the R-Pi should appear on your LAN
list, and you can talk between them. With luck, the BBbl will be reachable
too -- if the R-Pi passes hostname information from it to the router.
The only way to reduce the latency further would maybe be to use a
small four-port switch and CABLE the BBbl, R-Pi, AND laptop through the
switch (and maybe run DHCP on one of the nodes, so it can assign IP #s to
the other two). After all, the R-Pi4 has gigabit ethernet -- which probably
out-performs WiFi, and would be the fastest connection between the R-Pi and
laptop (unless the laptop only has 100 speed).
--
Dennis L Bieber
--
For more options, visit http://beagleboard.org/discuss
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