On Tue, Nov 22, 2016 at 1:20 PM, <[email protected]> wrote: > Hello All, > > I'm using BeagleBone Black as a TCP client which sends a TCP packet every 5 > seconds and the same packet is echoed by the server immediately and I'm > measuring the RTT (Round Trip Time). I'm using Edimax WiFi USB adapter. The > RTT measured was ridiculously high (400ms) and I eventually found out its > because the BBB suspends power to the adapter every few milliseconds (if > there is no activity). I can see the current toggling between 80mA and 0 > through an ammeter. Its because of this toggle, the RTT shoots up. I have > disabled the auto suspend for the USB. Some observations > > The same WIFI adapter plugged into a computer (Linux and windows) running > the same code works fine (with and without change to the autosuspend > settings). No toggling of power and a steady 40ms RTT is observed. Also blue > LED on adapter is stable. > I powered the the USB through a hub(powered externally) and connected it to > BBB and it still exhibits the issue > The toggling of power can be observed with the blue led on the edimax > adapter which remains constant when connected to other computers but blinks > when connected to BBB. Cross checked with an ammeter. > When I keep the adapter busy on BBB (by sending the packet every 500ms > instead of 2s), the adapter consumes a steady 80mA and the RTT is stable at > 40ms > > > I have played around with the autosuspend settings (by writing -1 to > autosuspend for the usb device), powered through hub etc. but the problem > persists.
Have you disable power management? sudo iwconfig wlan0 power off Regards, -- Robert Nelson https://rcn-ee.com/ -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/CAOCHtYguq%2B%3DbuVYawp6M9g8TsMwbxsJ9cROsXPrZwN_KSkD8nA%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
