ENGR2210 14 February 2012
Lab 2b - Project Component Guides
AKA “But We Already HAVE a Lab Due!”
Due: 17 February @ 9am
Step 1: Don’t Panic.
Step 2: In preparation for your upcoming projects, we would like you to do a bit of research on one topic and write a short guide on your findings. We’re looking for a 1-2 page PDF description (definitely no more!) including the following information (or other relevant data):
These reports will be compiled into a reference dictionary which we will then make available to the entire class! The idea is to divide up the research such that all of the groups can consult this “dictionary” during the project phase, and be able to use it to select appropriate parts and design accordingly.
These specifics are annoyingly specific. Please follow them anyway.
You must email your report by 9am on the 17th of February. Sending them in on the 16th would make your instructors happier. Your email should have the final report attached as a PDF, and a zip, tgz or tbz2 file containing all images used in the report. You must attach the zipfile of images in addition to the PDF - the instructors will be assembling a single document containing all of this data, and having the images separately will greatly simplify the process.
In return, you will get a pretty PDF of everybody’s reports. This PDF will also be posted to the web, in the hopes of being useful to other people.
Servos + Continuous Servos
Rack and Pinions
Acme Lead Screws
Extruded Aluminum (80/20)
Mecanum / Omni Wheels
XBee / Zigbee
JeeNode / RFM12B
Teensy / USB
Real Time Clock
Global Positioning System (GPS)
Example Topic by Chris Murphy
GPS + Onboard Directional Antenna
GPS with Antenna Connector
Helical Omnidirectional Antenna
All images are courtesy of http://www.sparkfun.com, licensed under CC BY-NC-SA 3.0.
GPS receivers interpret transmissions from a network of satellites to estimate their location.
What To Look For
Besides latitude and longitude, some GPS also report heading, speed, or other attributes. Some are equipped with a Pulse Per Second (PPS) connection, which provides a square wave signal closely synchronized (within 50ns - 1us!) with official atomic time. Also look for the Time To First Fix (TTFF) to determine how long you’ll wait after giving the module power.
How Is It Used
Given the diversity of GPS receivers, usage can vary. Broadly speaking, GPS modules are powered by a low voltage source (3.3 or 5 volts) and use tens of milliamps of current. They typically are connected via some form of serial connection, either I2C, SPI or TTL serial. Data is nearly always reported as ASCII formatted NMEA strings, which must be parsed.
Many different GPS chipsets are available, with different capabilities. Many modules are easily available from Sparkfun and Adafruit, with costs ranging from $30 to $100.
Advantages and Disadvantages
GPS is a wonder technology, but has drawbacks. First, it only works when it has a clear line of sight to the sky. Second, GPS consumes a fair amount of power, and will drain batteries quickly.