The Complete Hardware Crash Course

The Complete Hardware
Crash Course
SXSW 2014
Denis Bohm 
denis@ﬁreﬂydesign.com

Andrew Sanderson 
andy@modernfuelproducts.com

Team
• Denis Bohm

• Andrew Sanderson

• Kyle Bohm

HO: Hands On
• Follow the tiny URL for details.

• Start anytime. Feel free to jump ahead.

• This is a workshop, so please ask questions.

• Keep it casual. Help each other out. Share
what you are doing with others.

• Introductions.

Introduction
• Why use open source?

• Overview of how to leverage open source
hardware & software.

• Tips to save iterations.

• Walk through the typical steps from
concept to production…

Our Focus
• Quantity matters (1,000 is hard)

• Starting from scratch vs iterating

• Production has unique requirements

Open Source Checklist
• Hardware (electronics, mechanicals)

• Firmware (RTOS, driver, app)

• Software (API, apps, storage, sites)

• Production (sourcing, ﬁxtures, program &
test, FCC testing)

• Tools (IDE, SCM, eCAD, mCAD)

Fireﬂy Ice Project
• Wearable & Internet of Things Platform

• ARM Cortex M3, Bluetooth 4.0 LE Radio,
USB, Accelerometer & Magnetometer,
Rechargeable Battery, etc…

• Open source hardware, ﬁrmware, software,
production (and a couple of handy tools)

• 1,500 Units for First Customer

HO:Try It Out
• Instructions @ http://tinyurl.com/loc4qne

• Open the Fireﬂy Utility app

• Wake & connect to the Fireﬂy Ice in your
parts kit

• Play with the LEDs, check the battery level,
and name it

Process
• Now we are going to walk through the
process of designing a product.

• Normally, things happen intertwined and in
parallel… But we will discuss them as
separate items (industrial design,
mechanical design, electronic design, etc)

HO:View Mechanicals
• Instructions @ http://tinyurl.com/kx9nel5

• git clone https://github.com/denisbohm/
firefly-ice-mechanical.git

• open firefly-ice.3dm in Rhino3D

Industrial Design
• Materials, ﬁnishes, colors

• Shape, locations of all visible features: LEDs
& USB Connector, impact on PCB

• Markings: Logo,Word-marks, FCC ID, etc

• Mechanical considerations: seams, mold
lines, etc…

Mechanical
Considerations
• Design for ease of assembly (no rework)

• Design for molding (price, 4 pieces)

• Robust design (drop test, USB wrenching)

Mechanical Design
• Light pipes, color mixing, isolation, co-
molding

• USB opening (robustness, splash prooﬁng)

• Battery swell (add battery to 3D model)

• Wire management (photos)

• Mold design, surface ﬁnishes (draft, add
plastic), thickness (drop test, opaqueness)

HO: Edit Mechanicals
• Instructions @ http://tinyurl.com/l38r5az

• Increase the post length

• Export to STL for prototyping

Mechanical Prototyping
• 3D Printing (Price vs Time) (Personal &
Outsourced)

• Milling (Personal & Outsourced)

• Sections vs whole parts

• Production materials vs prototyping

• Colors & Finishes (sand, plate, paint, etc)

Mechanical Future
• Band-Aid:Thinness & Flexibility

• Waterproof: Charging

• Clothing: Power & Communication

Software
• CoreBluetooth, USB HID Manager

• SDK API: detour, executor/observable,
manager, sync

• App: discovery, connect, communicate,
active/inactive, background/foreground

HO: Using the API
• Instructions @ http://tinyurl.com/knmmxod

• git clone https://github.com/denisbohm/
firefly-ice-api.git

• open MacOSX/FireflyGame/
FireflyGame.xcode

Q & A
• And now for a short intermission…

Production
• Manufacturing Plastic Parts (Molds (time) +
sampling and tuning, then production run)

• Sourcing Components (BOM Tool)

• PCB Fabrication & PCB Assembly

• Programming & Test (Fixture + Fireﬂy Tool)

• Final assembly (PCBA + Battery + Plastics)

Test Fixture
• Mechanical design - spring pins for test
points

• Electrical design - PCB for mounting spring
pins and eliminating wire management

• Connectors (SWD, USB, battery, etc…)

• Software design - program & test software
using SWD

HO: Program & Test
• Instructions @ http://tinyurl.com/ls7yt33

• Connect Test Fixture to laptop

• run FireﬂyTool

• press PCBA into ﬁxture until complete

• connect and uniquely name your device

Firmware
• Source code: src/*.c,h

• Boot loader, main firmware, test firmware,
SWD programming firmware

• Memory map & placement, startup code

• Bluetooth Profile / nRFgo Studio

• Hex & Elf

HO: Firmware
Development
• Instructions @ http://tinyurl.com/lyp6p3b

• Debug hardware: JTAG, SWD, Cables

• Target hardware: Fireﬂy Ice PCBA

• Tool Chain: gcc, gdb, FireﬂyFlash

HO: Electronics
• upverter @ http://tinyurl.com/mx8lv55

• PDF @ http://tinyurl.com/m9rcju5

• Schematics & Board Eagle ﬁles on GitHub

• Multiple sheets & 4 signal layers

• CadSoft EAGLE Layout + Schematic
(Hobbyist $169, Standard $575)

Electronics
• Eagle 6

• Firefly Ice: firefly-ice.sch,brd

• Fixture: firefly-ice-fixture.sch,brd

• Parts Library: firefly.lbr

• Sourcing attributes on each component

Schematic
Considerations
• Power domains (voltage, switchable,
translation)

• Busses (pin count, speed, power,
robustness)

• Probe points (SWD, switches, USB, etc)

• Wires vs SMT (motors, batteries, etc)

• Power, availability, dimensions, ﬁne pitch

Layout Considerations
• Power planes, RF clearances, crystals

• Probe pads (SWD, clearances, 1 sided)

• Layers, pitches, in-pad/micro/blind/tented
vias

• Markings (copyright, model, revision, pads,
placement)

• Panelization (milling, mouse bites, ﬁducials)

Expansion Connector
• 6-pin low proﬁle SMT connector (2.25 mm
+ 2.5 mm = 4.75 mm)

• 3 power pins: unregulated voltage (5V to
3.5V), system voltage (2.2V), ground

• 3 data pins: I2C SDA, SCL, INT (or UART,
or Low Energy Sense, or analog
comparator, or GPIO)

HO: Sourcing & BOM
• Instructions @ http://tinyurl.com/lhmx5ha

• A prebuilt BOM release is in the GitHub
ﬁreﬂy-production-tools/releases repository

BOM Tool
• Reads sourcing attributes from schematic

• Gets pricing information via OctoPart

• Generates Bill Of Materials

• Generates purchasing quantity for each
distributor

HO: PCB To 3D
• Instructions @ http://tinyurl.com/k9ualyy

• A prebuilt PcbTo3D release is in the
GitHub ﬁreﬂy-production-tools/releases
repository

PCB to 3D
• Reads printed circuit board layout

• Writes Rhino 3D script

• Script creates PCB and places Rhino
components

• Useful for checking PCBA with enclosure

HO: Bluetooth 
Direct Test Mode
• Instructions @ http://tinyurl.com/kqvtjhe

• Use one firefly in direct test mode to send
test packets.

• Use another firefly in direct test mode to
receive test packets.

FCC
• Preparing a test device with SMA
connector

• Complete sample device

• Using a computer w/ USB for testing

• Documentation

• Markings

HO: Final Assembly
• Instructions @ http://tinyurl.com/lzxkkpk

• ﬁnal assembly into plastics (snap ﬁt)

Main Costs
• Electronic Components 100 $50, 1,000 $25

• PCB Fabrication & assembly (10 $250, 100
$50, 1,000 $25)

• Milling a plastic part $250+ ea @ FirstCut

• Mold $3,500+ ea, $1 per set MOQ 1k

• FCC Testing $6,500+ (w/radio, US only)

10 100 1,000
Components $50 $35 $25
Milled Parts $1,000 $0 $0
Molds $0 $14,000 $0
FCC $0 $6,500 $0
PCBA $250 $50 $25
Cost Each $1300 $290 $50
Total Cost $13000 $29000 $50000
Cost Progression

ManufacturingVendors
• Component Sourcing (meet, bundles)

• PCB Fabrication (local low volume)

• PCB Assembly (right ﬁt local, similar
projects & tools)

• Plastics Manufacturer (right ﬁt)

• Final Assembly & Test (self, interns) [learn &
improve the design]

DesignVendors
• Product Design (everything in parallel)

• Industrial & Mechanical

• Electronics & Layout

• Firmware

• Device API (iOS & Mac OS X,Android,
Windows, etc)

What’s on my Bench?
• CNC Milling Machine

• Microscope w/ Light, Camera, andVise

• Oscilloscope with uA Current monitor

• Soldering Station with SMT tweezers

• Power Supply (on/off), Multi-Meter (uA),
Wire Stripper, …

ThankYou
Questions, comments, ideas?

Denis Bohm 
denis@ﬁreﬂydesign.com

Andrew Sanderson 
andy@modernfuelproducts.com

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The Complete Hardware Crash Course

The Complete Hardware Crash Course

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