We met at the Cam Jam and I bought one of your Pi Robots. I built the robot in the Pi tradition of using what I had rather than buy another similar bits. So, the robot has a mk2 Pi, hand burned SD from the web site image, a Pi cam, WiPi dongle, GP Powerbank 4AH (to power the Pi) and the 4 x AA battery pack (for the motors). I plan to use a Nexus 7 for the hand controller and a Busbi 7 as a cheap backup.
The build was straight forward and the instructions clear.
At power on, the robot twitched and the Pi lights winked but the Nexus didn't pick up the Pi. Or the second or third time. Shuffled the driver board about and pluged in a monitor to see what was going on. During boot, this line appeared which seemed to be germain to the situation:
Starting advanced IEEE 802.11 management: hostapdioctl[siocswmode]: invalid argument
Failed
You were very helpful and quick with your reply to my query, thanks 
"I believe that replacing the driver line with driver=nl80211 in you /etc/hostapd/hostapd.conf should work. If it doesn't then you may need to remove the patched version of AdaFruit's hostapd (see their tutorial for an explanation). This is done by running the following from the Pi command line
sudo mv /usr/sbin/hostapd /usr/sbin/hostapd.ADA
sudo mv /usr/sbin/hostapd.ORIG /usr/sbin/hostapd "
As it turned out both were required before the Nexus picked up the Pi.
After many attempts involving repowering the robot, the Nexus eventually got an IP address and keying in the server IP (I suppose) into the nexus, got a rather short lived (5 seconds) poor quality video feed from the robot but no controlling joysticks. Further attempts failed to collect an IP address.
As there is no way to close down the Pi cleanly, I was pulling the power to shut down which had the effect of corrupting the SD card about half the time. Ended up with two cards on the go, one in use, the other being reburned.
Using a Maplin USB plug, I made up a short, direct power line between the Pi and the Powerbank. SD card corruption seems to have stopped. I think that a lot of the USB to micro USB leads were not designed to take the current that a Pi takes and so loose vital volts along their length leading to weirdies at the Pi.
I tried using the Busbi and it had more success in getting an IP address but only just. Didn't get a video feed but was able to pan and tilt the camera from the right joystick. But only the once but nothing crashed so I played with it for a while.
Both tablets said that the signal strength was excellent but were constantly trying to obtain an IP address and failing. The information provided by the tablets is a bit sparse for trouble shooting so I fired up my windows 7 laptop which I hoped would give more clues.
The first try came up with an invalid IP address format but the second attempt got through and, using Chrome, gave video feed and both joysticks functioning using the mousepad and left key to drive the joysyicks.
Pan and tilt tested OK, motor drive right, left tested OK.
However, it seems that this, too, was a once only function. No success since. And the tablets still don't pick up an IP address. Next, I'll try it with the notebook.
AndrewStatistics: Posted by ayoungtech — Wed Feb 19, 2014 12:46 am
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