CPSC 462 - TA
From Catholicpenguin
This page is meant as a storage place for some resources related to the project portion of the 462 class.
Contents
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General Things
- Final Project Thoughts - Read this first for general info related to the final projects.
- Tips On Electronics - Email sent by a professor during my senior design, with thoughts that are still relevant for ya'll.
Good Electronics Websites
- http://www.kpsec.freeuk.com/index.htm - Great site for info on the basics of using LEDs, transistors, etc
- http://www.play-hookey.com/ - Another good practical electronics info site
- http://www.sparkfun.com/commerce/tutorials.php - Very good tutorials for embedded electronics
- http://www.adafruit.com/ - Parts and stuff
Question and Answer
Driving LEDs
First, get a basic understanding of how to drive LEDs, then read the page on Wikipedia about LEDs for good measure. TheLEDLight also has some good information on LEDs.
LEDs come in various types. Standard red is the cheapest, but Mouser, etc, has all sorts of colors. You can also get RGB LEDs, which have red, green, and blue LEDs built into a single package. In addition to all the usual places, we've had good luck w/ http://www.superbrightleds.com/.
SparkFun has lots of things about LEDs. In particular, their LED matrix controller schematic might give you some ideas on how to drive lots of LEDs.
For driving normal-current LEDs, many standard logic chips such as shift-registers can be used (see the SparkFun example above).
For driving high-current LEDs, or switching lots of LEDs in a row, use a darlington transistor array. TI's data sheet gives a good example of the different part numbers. They are all ULN200# (1-4) chips.
Other random stuff:
- Cool website on multi-touch LED display: http://cs.nyu.edu/~jhan/ledtouch/index.html
OP-Amps
From the Tips On Electronics page above: "Op Amps: LF347. This is a quad FET input opamp that I highly recommend (over the 741 or other non-fet input opamps). Unless you have a reason for not doing so (e.g., you need higher performance) I'd suggest you use this. "
Enamel wire
From Wikipedia: "Enameled wire is copper wire coated with a very thin insulating layer. It is used in applications such as winding electric motor coils, speakers and transformers. It is also used in the construction of electromagnets and inductors."
Mouser appears to sell "magnet wire" on at least one page: http://www.mouser.com/catalog/635/1032.pdf
Someone should call Mouser, Digi-Key and see what their sales representatives suggest. Let me know and I'll update this section.
Standard Logic
Standard logic is chips which start w/ 74xx or 4xxx, and perform simple, standard function such as shift-registers, AND/OR gates, etc. They are often useful in interfacing microcontrollers to custom circuitry.
- Wikipedia has a good overview of 7400 and 4000 series chips, including a list of the part number<->function mapping for both series.
- OnSemi also has a good standard logic breakdown by function.
A note on the numbering. HC == high speed. Other crud at the front or end of the part means different things but generally they are logically equivalent.
A note on datasheets: Since these are standard logic, they are available from a million different vendors. Where possible, I've linked to a few datasheets below. However, google yourself. In terms of readability, I prefer sheets by: National, Fairchild, OnSemi, NxP, and last TI.
See also: http://www.ece.vt.edu/cel/datasheets/devices.html
In lab, we have the following chips available. The parts in bold are ones that you might actually use for something, in my opinion.
- 74HC00E H 9418 - Quad 2-Input NAND Gate - OnSemi TI Fairchild
- 74HC02AN - Quad 2−Input NOR Gate - OnSemi TI Fairchild
- 74HC08AN - Quad 2-Input AND Gate - OnSemi TI Fairchild
- 74HC10N - Triple 3-input NAND gate - NxP
- 74HC11N - Triple 3-input AND gate -NxP
- 74HC138B1 - 3-to-8 Line Decoder - OnSemi TI Fairchild
- 74HC139N - Dual 2-to-4 Decoder/Demultiplexer - OnSemi Fairchild
- 74HC154N3 - 4-to-16 Line Decoder -Fairchild
- 74HC157N - Quad 2-Input Multiplexer - Fairchild
- 74HC161N/74HC163N - High-Speed CMOS Logic Presettable Counters - TI National
- 74HC164B1 - 8-Bit Serial-In, Parallel-Out Shift Register - Fairchild
- 74HC165N - 8-bit parallel-in/serial out shift register - NxP TI
- 74HC174B1 - Hex D-type flip-flop with reset; positive-edge trigger - NxP
- 74HC193E - Presettable synchronous 4-bit binary up/down counter - NxP
- 74HC240AP - Octal buffer/line driver; 3-state; inverting - NxP
- 74HC244N - Octal 3-State Non-Inverting Buffer/Line Driver/Line Receiver - Fairchild OnSemi
- 74HC273N - Octal D-Type Flip-Flops with Clear - Fairchild
- 74HC30B1 - 8-Input NAND Gate - National
- 74HC393N - Dual 4-bit binary ripple counter - NxP
- 74HC4020N - 14-stage binary ripple counter - NxP
- 74HC4040AP - 12-Stage Binary Counter - Fairchild
- 74HC4051N - 8-Channel Analog Multiplexer - Fairchild
- 74HC4066B1 - Quad bilateral switches - Fairchild
- 74HC74AN - Dual D-type flip-flop with set and reset; positive-edge trigger - Fairchild
- 74HC85E - 4-Bit Magnitude Comparator - National
- 74HC86AP - Quad 2-Input Exclusive OR Gate - Fairchild
- MAX6957
We've also got quite a few DIP sockets that you can use for standard logic or other chips.
ADC basics
First you'll want some background on analog to digital converters. Ugh. Unfortunately, most of what I could find online is terrible in terms of simple explanations. If you haven't googled around already, I would read these links:
- http://www.seattlerobotics.org/encoder/jul97/basics.html
- http://www.embedded.com/217700911?cid=NL_embedded
The ideas listed on that page also provide a good place to start with the ADC.
I would start like this: 1. First, when starting, always hook a protection resistor up in series with the ADC in case you mis-wire something. A protection resistor is simply a resistor, perhaps around 10K ohms which you place inline with the ADC pin on the Cypress device and the circuit you are connecting to. So it should look like:
2. Setup the Cypress device so you can read analog values in and print them out over the serial port. Set it up so that it continuously reads values and prints them out, say once a second.
3.
- Connect one of the power supplies in lab, the ones with the variable output knob. Attach a multimeter to the circuit as well so you can measure what the power supply is outputting.
- Turn the knob all the way down. The multimeter should read close to 0 volts. At this point, the output from the ADC should be close to 0.
- Slowly turn the knob on the power supply up until the multimeter reads around 2.5 volts. The output from the ADC should change.
- Turn the power supply until it is around 5 volts. The ADC should now output the maximum value it cna measure. The exact number depends on the number of bits of resolution. For 8 bits, this will be 256. 10 bits, 1024. 16 bits, 65536, etc.
4. Now, instead of the power supply, try building the potentiometer circuit from the above link, and then the CdS Cell circuit.
Other Stuff I haven't had time to organize yet from last semester
Sources for Wireless communication
- 802.11 access point such as La Fonera
- Pro: High speed, serial interface, runs Linux, high range
- Con: Somewhat expensive, another component to deal with in your system design, requires setup and installation of linux on embedded device, large.
- ~$40
- XBee ZigBee communication
- Read up about ZigBee if you're not familiar
- Pro: Uses ZigBee, so reasonable range, multi-device capable, small, serial interface
- Con: Somewhat expensive, will for sure need at least two (one for embedded system, one for computer)
- ~$30-40 I think
- Very Simple Serial Radios
- Pro: Very simple -> write data from serial port at 2400 bps -> goes out on radio for all to hear. Easy to interface with.
- Pro: Cheap
- Con: Each module is one direction only, so you'll need two per side
- Con: Slow, not long range
Information about using 802.11 AP as a Linux based embedded computer
OpenWrt is a linux distribution designed for running on wireless access points. Many models are supported, but probably the one I recommend most is the La Fonera, as it has easy access to a serial port and GPIO pins.
Information on how to install OpenWRT on the device can be found on the OpenWRT Wiki. The information is a little confusing, so I'll put up more straightforward directions if anyone cares.
Triangulation using audio
Controlling high-current / high-voltage devices from the EB63 using relays
See this excellent page on how to use a transistor, relay, and protection diode to achieve switching of high voltages and high currents.
In particular, look at the section titled Choosing a suitable NPN transistor.
