Pi doesn't recognize WiFi dongle on reboot

chezstgeorge · February 9, 2015, 5:34pm

I am having an issue with my Pi rebooting and discovering WiFi. I had to switch out my fermentation chamber for a newer model. I unplugged all of my components after powering down and then once I had completed the switch I re-attached all components and powered up. The Arduino is working great as always but my Pi isn’t configuring the WiFi. has anyone else had this problem? I will troubleshoot this week and hopefully I can figure it out. Likely it will be my friend who is a programmer and has more understanding of the code. Haha.

mikmonken · February 9, 2015, 6:21pm

Does the dongle get power? Mine can take a while for it to start flashing up to 20 mins unless I unplug and put it in a different port. Mines the Edimax one that’s recommenses

chezstgeorge · February 9, 2015, 6:36pm

I don’t think it gets power. I used a WiPi dongle and it glows blue when powered. We had to reprogram the Arduino a couple of weeks ago because of an issue with a data log name which had characters. We rebooted after fixing the issue and it powered up fine. I’m not sure why it didn’t work this time. Should I try switching the ports?

mikmonken · February 10, 2015, 6:37am

It worked for me! But mine always comes on eventually it just cAn take a long time

hughmc · February 10, 2015, 6:48am

wifi on my pi is super touchy, sometimes i think it’s the signal strength but sometimes not. try sudo ifdown wlan0 followed by ifup. sometimes that kicks it into gear (that is of course if you can get a keyboard or an ethernet cable into it, i sometimes had to just plug the keyboard in, log in, down and up the card without seeing what im doing!)

Elco · February 11, 2015, 11:37am

We wrote this shell script to automate that:

github.com

BrewPi/brewpi-script/blob/master/utils/wifiChecker.sh

#!/bin/bash
### Wifi Checking/Re-Enabling script for Brewpi
### This checks every 10 minutes to see if the wifi connection is still active via a ping
### If not, it will re-enable the wlan0 interface
### Geo Van O, Jan 2014
### User-editable settings ###
# Total number of times to try and contact the router if first packet fails
MAX_FAILURES=3
# Time to wait between failed attempts contacting the router
INTERVAL=15
###  DO NOT EDIT BELOW HERE!  ###

### Check if we have root privs to run
if [[ $EUID -ne 0 ]]; then
   echo "This script must be run as root: sudo ./wifiChecker.sh) ($(date))" 1>&2
   exit 1
fi

if [ "$1" = "checkinterfaces" ]; then
    ### Make sure auto wlan0 is added to /etc/network/interfaces, otherwise it causes trouble bringing the interface back up

This file has been truncated. show original

It is added to /etc/cron.d/brewpi in the brewpi installer if you say yes to that prompt:

pi@brewpi ~ $ cat /etc/cron.d/brewpi
stderrpath="/home/brewpi/logs/stderr.txt"
stdoutpath="/home/brewpi/logs/stdout.txt"
scriptpath="/home/brewpi"
entries="brewpi wifichecker"
# entry:brewpi
* * * * * brewpi python $scriptpath/brewpi.py --checkstartuponly --dontrunfile $scriptpath/brewpi.py 1>/dev/null 2>>$stderrpath; [ $? != 0 ] && python -u $scriptpath/brewpi.py 1>$stdoutpath 2>>$stderrpath &
# entry:wifichecker
*/10 * * * * root sudo -u brewpi touch $stdoutpath $stderrpath; $scriptpath/utils/wifiChecker.sh 1>>$stdoutpath 2>>$stderrpath &

If you disabled it, you can re-enable it by removing the ~ in # entry:~wifichecker and running /home/brewpi/utils/updateCron.sh