Toor con2010 - w0z

1. amanda w0zniak

2.  Electrical engineering is a discipline like
any other, you learn by experience and
mistake.
 The design process is part intuition, part
art and all iterative tenacity.
 There is no “black magic,” about
hardware, just physics and RTFM.
 Dive in with an Arduino and ‘The Art of
Electronics,’ and don’t wuss out while
you’re getting up the learning curve.

3.  When you are building hardware, you
have to physically instantiate your idea.
 Each instantiation (required to debug
problems and test concepts) takes time,
money, materials and skills.
 Compile times are counted in weeks.
 A working design means you are only
15% done and that the fun part is over.
 Software project models do not apply.

4.  Hardware is made of PARTS: aka resistors,
ICs, switches, batteries and wires combine
to make CIRCUITS
 You buy parts from distributors like Digikey
and Mouser
 Every part has a data sheet
 For a prototype, you can connect parts by
hand ad-hoc and then hack away
 If it works, stuff happens, you move on
 If it doesn’t work, you RTFM

5.  EAGLE, Cadence, PCBXpress, Mentor
 CAD = Computer Aided Design
 We don’t make circuit boards by drawing out
traces by hand and masking photo resist with
tape (why it’s called “tape out”)
 Instead, we use 15 year old software suites

6.  A “part” or “device” in CAD consists of a
“footprint/package” and a “symbol”
 Your “library” holds all of the devices for your
design
= +

7.  You “design” in a “schematic”
 The CAD program (eagle, cadence, pcbxpress)
extracts a “netlist” from the schematic to create
a “layout”
 You “route” all the IRL copper to connect the
devices according to your schematic design.

8.  Once you are done with your “layout,” you
extract “gerbers,” aka executable design files
 A “fabrication house” takes your gerbers and
makes a printed circuit board for you
 An “assembly house” takes your PCBs and
your physical parts, your BOM list and
assembles your hardware
 All of these steps can be done by hand, and
all the steps are required even with DIY

12.  non-DFM device footprint
(YETDA! YETDA! YETDA!)
 Schematic symbol error
(rotated FET syndrome)
 Non-validated prototype (due
to part unavailability or failure
to schedule properly)
 Non-validated components
(sourcing from china or last-
minute substitutions)

14. you don’t need to be an MIT engineer

15.  Do not “begin at the beginning.”
 Start at the end.
 Estimate lead times: assembly,
fabrication, shipping and BOM cost.
 Back out cost vs. time and quantity.
 Select obtainable, known components.
 Curate your CAD library.
 Validate your design implementation.
 Iterate design through prototypes.

16.  A good designer considers every layer
of “fabrication,” from PCB limitations to
the end assembly method in order to
make a good design that can be built to
specification, on schedule and on
budget.
 Curate as you go. You will be too tired to
remember, let alone correct, any of your
implementation errors post-facto.

17.  a BOM is the list of all components that are
in your design (resistors, ICs, modules,
connectors, etc)
 Reference Designator (R1, U28)
 Component ID (Digikey/Mouser #)
 Component Count and Cost
 Footprint (SOIC-8, TSSOP, 0402)
 Use/Purpose/Function/Sub-circuit
 CAD Status

19.  Connections in schematics are called “nets”
 A “netlist” is the list of all the nets in your
design
 Use a netlist to validate what you built from
what you meant to build (LVS verification)
 Brandon & I co-wrote the netlist to keep the
signal names equal between the board and
the code.... in a spreadsheet

20.  there’s a full Eagle library, schematic,
layout, gerber package and BOM for the
ninja boards in my public directory
 download it, start messing around.
 http://web.mit.edu/~awozniak/www/ninjas/

21. but now we’re out of time

22. until next time...
http://www.adafruit.com/  tutorials