Robotics & Electronics

• Raspberry Pi WiFi

  Nov 14, 2012

  The Raspberry Pi is a $35 single-board ARM computer that runs Linux. If you don't yet have a Raspberry Pi, you can either order Raspberry Pi from Newark/Element 14 and get on in line waiting for the next batch or pay way too much for a Raspberry Pi from Amazon.com.

  Here are two nano-sized, low-cost, USB WiFi adapters that I have verified work on a Raspberry Pi ("Wheezy") right out of the box.

  

  The AirLink101 AWLL5088 Wireless N (0bda:8176 RTL8188CUS 802.11n WLAN Adapter) is shown on the left and the Edimax EW-7811Un Wireless N (7392:7811 EW-7811Un 802.11n Wireless Adapter Realtek RTL8188CUS) is shown on the right.

  Both of these WiFi adapters are based on the Realtek RTL8188CUS chipset. Drivers are built-in with Raspberry Pi Raspbian ("Wheezy"), the debian-based distro used by most beginners.

  Not only are they based on the same WiFi chipset, they are virtually identical in size too. These are "nano" sized which means they're not much larger than the USB connection itself.

  Since the Raspberry Pi only has 2 USB ports, you're most likely going to want to get a powered USB hub as well. That will allow for a mouse, keyboard, and the WiFi adapter with additional ports available for more devices.

• Setting USB Permissions for USBtinyISP in Fedora

  Aug 09, 2012

  If you try to use the USBtinyISP USB AVR programmer as a regular user in Fedora, you will get a permissions error like the one below.

  avrdude -p m328p -c usbtiny -e -U flash:w:test.hex
  avrdude: Warning: cannot open USB device: Permission denied
  avrdude: Error: Could not find USBtiny device (0x1781/0xc9f)
  
  avrdude done.  Thank you.

  In order to use the USBtinyISP without becoming root you will need to add a udev rule that gives regular users permission to use the device.

  su
  echo "SUBSYSTEM==\"usb\", ATTR{product}==\"USBtiny\", ATTR{idProduct}==\"0c9f\", ATTRS{idVendor}==\"1781\", MODE=\"0666\"" > /usr/lib/udev/rules.d/99-custom.rules
  udevadm trigger
  

  You should now be able to use the USBtiny with avrdude as a regular user.

• CadSoft Eagle 6.2 in Fedora 17 x86_64

  Aug 02, 2012

  I've been using CadSoft Eagle in Linux for years. But it's been a little while since I've had a chance to tinker with my robotics projects. Turns out the installatin isn't quite as simple as it once was. Here is how I got Eagle running in 64-bit Fedora 17.

  
  

• HP Pavillion dv2000 Motherboard Fix

  Aug 01, 2012

  Several years ago, my sister's HP Pavillion dv2000 series laptop died after about a year and a half. No video. Naturally, she brought it to me as I did spend my early 20's reparing laptops and the like. A quick search turned up dozens of other people experiencing the same exact symptoms with their dv2000 laptops just after one year. Of course the manufacturer warranty is only for one year. What few good mother boards were available were insanely expensive. I advised her to cut her losses and move on.

  I found this old HP laptop in my closet the other day. I had intended to donate it to Free Geek for parts. But, I happen to be in the market for a cheap laptop. Another search and I find out fellow geeks on the interwebs have determined the issue is with the video chip overheating. Reflowing the BGA chip often solves the problem. I figured it was worth a shot.

  

• FailureBot 5 - A Line Following Robot

  May 27, 2006

  FailureBot 5 - Complete Robot	FailureBot 5 Following A Line