NERP – next meetng 8/27 + notes from 8/13

The next NERP (Not Exclusively Raspberry Pi) meeting will be at 7pm Monday August 27th. The new regular format of the NERP meetings is

  1. a new user orientation (first session) at 6pm
  2. The regular meeting (second session) from 7-8:30pm.
  3. The after party which goes on until the building closes.

The orientation sessions help new users get their Raspberry Pis booted and quickly demo where the start buttons are in the operating system. The second session is a forum for talks, demos, free discussion, and questions. Subjects can be of general interest or advanced and highly focused. *

occidentalis – the black raspberry

The purpose of NERP is to promote discussion and exchange of knowledge and ideas. Interruptions and dumb questions are encouraged. The flow of a meeting can be deliciously chaotic.

I didn’t set out to take minutes at the NERP meeting last Monday, but there was so much good information flying around that it was hard to resist jotting some things down.

  • Drew demoed many of the apps that come with the pi by default.

  • Looked at Quake on the RPi. Learned about the Simple DirectMedia Layer (SDL) (“…a cross-platform, free and open source multimedia library written in C that presents a simple interface to various platforms’ graphics, sound, and input devices…”)
  • Looked at /opt/vc where the broadcom videocore libs and utils live. Note to self: some of the utils look useful for low level tweaking at run time.
  • Clarified the difference between Arduino and Rpi by running a blinky demo with the arduino hosted by the Pi
  • Cortex M-series is the microcontroller family of Arms. There are <$20 ARM M4 boards.
  • The logic level output lines are weak. Voltages are: USB = 5V, general i/o = 3.3V, HDMI = 1.8V.
  • It don’t mean a thing if you ain’t got that adafruit clear box and breakout board.
  • Everything is a file. How to do output in Bash:

echo “out” > /sys/class/gpio/gpio4/direction
echo “0” > /sys/class/gpio/gpio4/value
echo “1” > /sys/class/gpio/gpio4/value

  • The video output problem… There are cheap 3.5” video screens (for car rear view cameras) on amazon
  • From Jay: Demo of a Motorola dock for a phone for $55.   11.6” HDMI 1333 x 800. Works well with RPi.
  • Watch ebay, amazon, China direct sellers for cheap $15 -to $50 HDMI to VGA adapters.
  • In the initialization/setup tool set Pi to force HDMI so it doesn’t try to default to composite output at boot. It’ll get stuck there and won’t see the HDMI if plugged in later.
  • Pi has undocumented connectors for CSI (camera serial interface) and DSI (display serial interface) Broadcom is planning a backpack HDMI rez camera for RPi
  • The broken wireless driver problem is sometimes helped by using the Occidentalis v0.1 distro/mod from
  • All the cool kids are ditching plain Raspbian. Occidentilis (derived from Raspbian) is the one to have. It’s specifically for doing electronics. It has good support for SPI, I2C, one wire, and more WiFi sticks.  Black Raspberry – wheezy. Yes.
  • Drew will make a wiki at PS1 (DONE)
  • Computer vision is the killer app.
  • That, and network services that interact with the physical world.


*If you would like to show your work or lead a discussion on NERP, email ed at kineticsandelectronics dot com to set up a time.

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