Intro to CAD

From Class Wiki
Jump to navigation Jump to search

This page is for the Intro to Engineering ENGR 122 EE/CPE Section

Two Dimensional CAD

Persistence of Vision Bike Light Project

This project will use a 3.3 volt Arduino Pro Mini clone that you will design the circuit board, housing, and software for. Persistence of vision is a psychological effect that allows you to see two dimensional images that were created by one dimensional flashing LEDs. Here are some similar projects:

We will have an MMA8452 accelerometer that communicates via a serial I2C interface. The accelerometer will measure the angular acceleration, which will allow the velocity of the bike wheel to be calculated. This will make it possible to flash LEDs at the proper time intervals to spell words, draw pictures, etc., as you ride your bike down the road at night.

The power source for your POV device can be two or three AA, or AAA batteries. You need to design the packaging. Some suggestions that you can consider are:

Kicad Libraries

Footprints for CVPCB and PCBNew

EESchema Checklist

  • ATMEGA328P
  • MMA8452Q
  • MIC5205
  • Do you really want an LED to tell you the device is on? (I'm guessing probably not, so make sure you didn't put one in if you don't.)
  • Batteries
  • Programming cable connector
  • LEDs
  • Are the LEDs distributed over Ports B, C and D?
  • No errors in the design check?
  • Do you have the DOC linked to the datasheet for each important part?
  • Do you have the datasheet URL in the datasheet field for each important part?
  • Does your schematic look need and tidy?
  • Do you have pull up resistors on the I2C bus lines SCL, SDA, and SA0?

Example Schematics & Footprints

  • This is an example schematic. It has provision using jumpers K1 and P3 to select either two or three batteries and a voltage regulator, or two batteries without a regulator. You don't need to do this. I am doing it, so I can have a board that can be configured either way for debugging possible issues. I recommend picking one or the other power supply method.
  • Example Footprint Selection You need to select the Aerodyne_v2.pretty in the Preferences->Library Tables in CVPCB in order to find the special footprints.

Parts Ordered By Ralph

This is Ralph's parts order.

Kicad Videos and Other Information

Engineering_Electronics

Getting Started with Kicad

Setting Up the Environment and Getting Started

  • Some environment variables should be set such as the two below. Put them in your ~/.profile file at the end.
export KIGITHUB='https://github.com/KiCAD'
export KISYS3DMOD='/usr/local/share/kicad/modules/packages3d'
  • In order for them to be activated, you need to logout and login again, or if you don't want to do than right now you can also paste the two lines above into a terminal and start kicad from that.
  • Some environment variables should be set such as the two below. Put them in your ~/.profile file at the end.
export KIGITHUB='https://github.com/KiCAD'
export KISYS3DMOD='/usr/local/share/kicad/modules/packages3d'
kicad
  • If you want the 3D viewer to know about your Aerodyne_v2 parts, you need to put a symbolic link to the 3D parts in the /usr/local/share/kicad/modules/packages3d/ directory, by doing this from the directory containing the KiCadLib-master directory.
$ sudo ln -s /KiCadLib-master/3D /usr/local/share/kicad/modules/packages3d/3D

Make the Schematic in EESchema

You should have done this already.