Many product ideas require small low power connected devices. For example, many types of activity monitors and Internet Of Things applications. Learn how to take advantage of open source hardware and software to focus your efforts on the core value of your product that makes it unique. In this two and a half hour long workshop, we will cover how to leverage the Open Source Firefly Project hardware and software along with other open source components, such as ARM Cortex-M GNU tools, to create a new device. This includes customizing the electronics, mechanicals, and software. You will also be shown how to produce your device at low volumes and estimate the production costs. Bring your Mac Laptops. Devices based on the Open Source Firefly Project will be available for use by workshop participants to illustrate many of the steps in the process. Successfully program, test, and assemble a device and you can take it with you. (Information about the Open Source Firefly Project is at http://fireflydesign.com.)

1. The Complete Hardware
Crash Course
SXSW 2014
Denis Bohm
denis@fireflydesign.com
Andrew Sanderson
andy@modernfuelproducts.com

2. Team
• Denis Bohm
• Andrew Sanderson
• Kyle Bohm

3. 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.

4. 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…

5. Our Focus
• Quantity matters (1,000 is hard)
• Starting from scratch vs iterating
• Production has unique requirements

6. 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)

7. 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

8. 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

9. 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)

10. HO:View Mechanicals
• Instructions @ http://tinyurl.com/kx9nel5
• git clone https://github.com/denisbohm/
firefly-ice-mechanical.git
• open firefly-ice.3dm in Rhino3D

11. 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…

12. Mechanical
Considerations
• Design for ease of assembly (no rework)
• Design for molding (price, 4 pieces)
• Robust design (drop test, USB wrenching)

13. 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)

14. HO: Edit Mechanicals
• Instructions @ http://tinyurl.com/l38r5az
• Increase the post length
• Export to STL for prototyping

15. 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)

16. Mechanical Future
• Band-Aid:Thinness & Flexibility
• Waterproof: Charging
• Clothing: Power & Communication

17. Software
• CoreBluetooth, USB HID Manager
• SDK API: detour, executor/observable,
manager, sync
• App: discovery, connect, communicate,
active/inactive, background/foreground

18. HO: Using the API
• Instructions @ http://tinyurl.com/knmmxod
• git clone https://github.com/denisbohm/
firefly-ice-api.git
• open MacOSX/FireflyGame/
FireflyGame.xcode

19. Q & A
• And now for a short intermission…

20. 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)

21. 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

22. 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

23. 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

24. HO: Firmware
Development
• Instructions @ http://tinyurl.com/lyp6p3b
• Debug hardware: JTAG, SWD, Cables
• Target hardware: Firefly Ice PCBA
• Tool Chain: gcc, gdb, FireflyFlash

25. Q & A
• And now for a short intermission…

26. 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)

27. Electronics
• Eagle 6
• Firefly Ice: firefly-ice.sch,brd
• Fixture: firefly-ice-fixture.sch,brd
• Parts Library: firefly.lbr
• Sourcing attributes on each component

28. 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

29. 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)

30. 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)

31. HO: Sourcing & BOM
• Instructions @ http://tinyurl.com/lhmx5ha
• A prebuilt BOM release is in the GitHub
firefly-production-tools/releases repository

32. BOM Tool
• Reads sourcing attributes from schematic
• Gets pricing information via OctoPart
• Generates Bill Of Materials
• Generates purchasing quantity for each
distributor

33. HO: PCB To 3D
• Instructions @ http://tinyurl.com/k9ualyy
• A prebuilt PcbTo3D release is in the
GitHub firefly-production-tools/releases
repository

34. 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

35. 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.

36. FCC
• Preparing a test device with SMA
connector
• Complete sample device
• Using a computer w/ USB for testing
• Documentation
• Markings

37. HO: Final Assembly
• Instructions @ http://tinyurl.com/lzxkkpk
• final assembly into plastics (snap fit)

38. 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)

39. 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

40. 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]

41. DesignVendors
• Product Design (everything in parallel)
• Industrial & Mechanical
• Electronics & Layout
• Firmware
• Device API (iOS & Mac OS X,Android,
Windows, etc)

42. 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, …

43. ThankYou
Questions, comments, ideas?
Denis Bohm
denis@fireflydesign.com
Andrew Sanderson
andy@modernfuelproducts.com

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