NERP October 22 Summary
Last nerp, Drew got things going with another well produced demo of the Raspberry Pi doing hardware i/o. In keeping with the spirit of the season he and Bonnie King put together a network controlled musical multimedia Jack o’ Lantern that blinked and played mp3′s through browser interaction. There are lots of ways of doing physical i/o though an internet link. To my untrained eyes, the high points of Drew’s and Bonnie’s approach included
- ajax to help push the data back and forth between the web page and server
- the RPi gpio module for reading switches and turning on and off the lights
- the python thread class for allowing the RPi to blink the lights without stalling the program
- a hook to control mplayer to play the sounds.
Check out Drew’s full write-up on his Element14 blog http://www.element14.com/community/groups/raspberry-pi/blog/tags/pumpkin_pi
Joe Walnes, known for his PiCrust http://picru.st/ adapter board, was our dark horse presenter. One of his other Raspberry Pi based projects is a coding environment called quick2web for people who are new to web programming* and also for rapid prototyping of web connected hardware control. Joe demoed web-slider:
- …a mobile web-app that contains a slider bar…
- …that communicates to a Python program via WebSockets…
- …that adjusts an LED bar-graph.
- Then point your desktop or mobile browser to http://[hostname]:8888/. Try multiple browsers for fun.
The web interface allows multiple locations of interaction with the Raspberry-Pi through a browser. This is neat, but his main interest is in bringing a simplified, event driven programming model to beginning programmers. The demo made things like gui building and asynchronous hardware events look easy. When Joe’s quick2web environment takes off it will do for hardware-interactive web programming what the Arduino has done for microcontrollers and Libre development tools (gcc). I was pleased that Joe presented at nerp, and I hope he’ll do it again soon. Quick2web needs programmers. This is a worthy effort. Volunteer if you can!
*This is me.
Monday November 5
Ryan Pierce will show us how he is rewriting an Arduino 1-Wire library “…to be (mostly) non-blocking. My project is AC phase dimming with triacs while still reading temperatures… Each half of the AC sine wave is 8.333 ms. And reading a temp from 1-Wire is a 10 ms operation. So the new library allows me to start an operation, get a (nearly) immediate return, poll the timer for the AC to see if it is time to fire the triacs, go back to polling 1-Wire to see if it is time to bang a bit which should return (nearly) immediately, check the triac again, rinse, lather, repeat….. “
John Dolecki will bring his Robot to this meeting. He says “Please don’t expect techno mumbo jumbo from me as my programming skills are on the beginner level. I’m sure once you are introduced to Microsoft Robotics Studio, the C programming will look familiar to you.
Let the Robot Apocalypses start here!”
Sounds great, John!