Monday, November 30, 2015

Pi SSH Disconnects and Power Management

Solved an ongoing issue with the Pi, and that is I often come back to my computer with all of my SSH terminals disconnected.

I would log back in again, and check that the uptime was still days whereas I had been away for much less than that.  So I concluded the Pi hadn't rebooted, thereby disconnecting the terminals.

It always seemed to be after a somewhat lengthy time away, but sometimes not all that long (like a few hours).

I thought first it was possibly idle connections being cut.  I played around with some settings but it didn't really do much.



After some reading online, I decided to try looking into power management on the WiFi adapter.  This was the solution.  The stackexchange discussion which led me to the solution is here (link).

The adapter I use is the recommended adapter noted in a prior post (link).

The commands required are seen below.

$ iwconfig
wlan0     IEEE 802.11bgn  ESSID:"DV_2.4Ghz"
          Mode:Managed  Frequency:2.412 GHz  Access Point: 00:81:D8:D5:46:3C
          Bit Rate=5.5 Mb/s   Tx-Power=1496 dBm
          Retry short limit:7   RTS thr:off   Fragment thr:off
          Power Management:on
          Link Quality=70/70  Signal level=-34 dBm
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:0   Missed beacon:0

$ sudo iwconfig wlan0 power off

$ iwconfig
wlan0     IEEE 802.11bgn  ESSID:"DV_2.4Ghz"
          Mode:Managed  Frequency:2.412 GHz  Access Point: 00:81:D8:D5:46:3C
          Bit Rate=5.5 Mb/s   Tx-Power=1496 dBm
          Retry short limit:7   RTS thr:off   Fragment thr:off
          Power Management:off
          Link Quality=70/70  Signal level=-33 dBm
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:0   Missed beacon:0



After having run this command, the issue has not come up again.

A persistent on-boot configuration will likely be required.  I doubt this command stays in effect across reboots.


No comments:

Post a Comment