In this one-month workshop, we configured a Raspberry Pi as a WiFi access point and demonstrated how it can control stepping motors and other hardware. Most students bought a CanaKit Raspberry Pi 2 Ultimate Starter Kit. For $8 each, I supplied baggies with additional LEDs, a ATMega328P processor, and a couple other components so that they could upload and run ATMega328P assembly programs from their Pi. These files give all the details.
Information for Scientists and Engineers who wish to read technical Japanese literature.
This is my favorite picture of Half Dome, Nevada Falls, and Vernal Falls from Glacier Point. I took this on June 15, 2005, during a hike with one of my daughters to Glacier Point from Yosemite Valley via the 4-Mile Trail.
Mt. Hoffman is located near the center of Yosemite National Park. It is only 10600' high, but, because of its central location, it has one of the most spectacular panorama views in the park. To the South is Glacier Point and Senital Dome above Yosemite Valley, to the SouthEast is Cloud's Rest, Half Dome, and in the distance Mt. Clark and other peaks of Yosemite's southeast corner. To the East is Lake Tanaya, Cathedral Peak, Tuoloumne Meadows, and the peaks from Mt. Dana to Mt. Lyle. More peaks and valleys are visible as one turns from the northeast to the southwest.
Here are pictures and a description of a hike to the top of Half Dome starting from the Sentinel Dome parking lot.
The Cloud's Rest trail from Tenaya Lake is described here with a Table of elevation changes.
Next to Tioga Pass at the east end of Yosemite National Park is Mt. Dana. From its 13061-foot high summit, one can take in a spectacular 360-degree view with Mono Lake to the East, Tuoluomne Meadows to the West, and the Sierra Crest to the North and South.
We took a drive over Tioga Pass on May 22, 2008, to see the remaining snow, visit Mono Lake, eat at the Mono Cone, and drive the June Lake loop. These are some of our pictures.
This easy hike takes one up to what is left of a mining boom town, and a series of meadows and lakes heading toward Mt. Conness.
The Chilnualna Falls trail near Wawona is a great hike for the early spring or late fall when the higher trails are unavailable.
A collection of pictures showing the ranch flora and fauna and our surrounding gardens.
By using well-known techniques, we reduced our ranch energy consumption by 50% without sacrificing quality of life. The repair history for our 2003 prius may also be useful.
The web site of a group of llama-owning hikers who go on monthly trips into the Sierra Nevada mountains.
When the sun is at your back, the blue sky up ahead of you is largely horizontally polarized. Using a vertical polarizing filter makes it darker and lets the trees and clouds stand out better. Similarly, when sunlight reflects off of water, it is also largely horizontally polarized. Using a vertical polarizing filter then blocks out the reflection and lets you see into the water. This picture shows these effects.
A collection of links I recommend for voters in the 2008 presidential election.
I needed an inexpensive PC to use when I teach Linux at Los Angeles City College Community Services. The classes install Ubuntu Linux, do networking games, compile a custom kernel, set up a full range of servers (DHCP, DNS, Apache, vsFTP, SSH, CUPS, Samba, SMTP, POP3, IMAP, and Mail list), and demonstrate a Web Database Application using MySQL and PHP. The Walmart TC 2512 comes with gOS system which I replaced with Kubuntu 8.04, 512 MB which I augmented to 1.5 GB, and a single ethernet interface to which I added another. Total cost $250 (plus tax and shipping).
This very low-cost PC is an excellent computer for folks who just want e-mail, web browsing, word processing, printing, and digital camera interfacing. It can, however, do far more. Here are instructions for setting it up with Ubuntu and for dealing with its unsupported modem.
Ubuntu has little difficulty configuring screen resolution on display hardware that automatically reports its capabilities using the DDC and EDID protocols, but older hardware needs special care. These notes are designed to help new Ubuntu-10.04 users get the expected resolution from their older hardware.
A summary of a talk given to the San Gabriel Linux Users' Group about the Linux Boot Process and how to make boot diskettes and boot CDs. This info is dated, but folks seem to still find it useful.
This note shows how to create a safe place to put important information that won't be compromised even if your computer is stolen.
A program that helps explain the purposes of various files in the linux system. It is gradually becoming obsolete since I have not had the time to keep its database up to date.
A list of good non-fiction books I have enjoyed reading over the past few years
Details of an altitude problem discovered when using my Mavica CD500 camera at altitudes above about 11,000 feet.
Electronics has changed considerably since my days with vacuum-tubes, and every few years I get the urge to build some electronic gadgets using the latest technology. I will add projects to this list as they reach a presentable stage.
This demo board contains a FTDI FT2232C USB interface chip, a PIC16F877A microcontroller, and auxiliary circuits to allow convenient digital I/O, A/D conversion, and temperature measurement with DS18S20 single-wire sensors. This device makes it relatively easy to build a low-frequency oscilloscope and to monitor a wide variety of remote sensors.
I am interested in remote monitoring of various temperatures around the ranch. The first step is to calibrate the thermometers.
Various thermometers around the ranch are automatically sampled by a DLP-2232PB-B sensor every 15 minutes. These are the most recent readings. The water pump activity is also monitored and the past 48 hours of water usage are displayed. I plan to add computer monitoring of the total ranch electrical power usage as well.
The Mavica CD500 camera writes to mini-CDs (8 cm dia) and also communicates using a USB 2.0 connection. Both interfaces work fine with Linux, but I also wanted to have my computer able to remotely operate the camera.
These notes explain what was involved in outfitting two of our grandchildren with a Raspberry Pi. The long-term goal is to get them understanding computer programming and electronics.
With care, the lens of the Raspberry Pi Camera may be refocused or removed, making it useful for extreme close-up imaging or as an imaging system for a microscope or telescope. This is a discussion about these possibilities.
These describe the features of the $35 Raspberry Pi computer and how it can be used to learn computer programming languages such as Python, C, C++, etc. With the Gertboard add-on board, one can also learn microprocessor assembly language programming and the fundamentals of robotics.
I tried to ignore WiFi as long as I could, but use at the schools where I teach and the needs of occasional visitors forced me to learn about it. These notes explain setting up a WiFi access point on a Raspberry Pi and also on a my Ubuntu yosemitefoothills.com server.
Spending a summer getting acquainted with a nifty microprocessor and companion add-on board. The immediate goal is automating the data acquisition from a Geiger counter.
An ordinary Geiger counter is connected to a RaspberryPi/Gertboard system and used to monitor Solar particle events and cosmic rays.
A summary of an August 8, 2007, presentation given to the Fresno Open Source Users Group (FOSUG) that describes how I am connecting electronic gadgets to my computer using a USB connection and interfaces from DLP Design. The Linux software is described and all C and assembly code is linked.
Last updated: September 27, 2015
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