The Complete Hardware Crash CourseSXSW 2014Denis Bohmdenis@fireflydesign.com

Andrew Sandersonandy@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

Q & A

• And now for a short intermission…

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

Manufacturing Vendors

• 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]

Design Vendors

• 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, and Vise

• Oscilloscope with uA Current monitor

• Soldering Station with SMT tweezers

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

Thank You

Questions, comments, ideas?

Denis Bohmdenis@fireflydesign.com

Andrew Sandersonandy@modernfuelproducts.com

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