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 <https://www.amazon.com/Edimax-EW-7811Un-150Mbps-Raspberry-Supports/dp/B003MTTJOY/ref=sr_1_4?s=pc&ie=UTF8&qid=1461119085&sr=1-4&keywords=usb+wifi+adapter>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
1. 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. 2. I powered the the USB through a hub(powered externally) and connected it to BBB and it still exhibits the issue 3. 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. 4. 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. Can anyone suggest if I'm missing something obvious. -- 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 beagleboard+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/b353a7b5-38a5-416f-a4a1-096f7b7c2ee7%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
