HOW TO PUT A THING ON THE INTERNET OR: LESSONS LEARNED WRITING SOFTWARE AT WHISKER LABS Evan Meagher May 2017 

May 2017 @evanm Software at Whisker Labs Who? My name is Evan Meagher. It’s pronounced “mar”. I lead software development at Whisker Labs. I used to work at Twitter. Fig. 1—Portrait of the speaker eating pizza. 

May 2017 @evanm Software at Whisker Labs Table of Contents Framing the narrative Lesson 1: Mind your protocols and queues Lesson 2: Err on the side of conservatism Lesson 3: Everything old is new again Closing & Questions 

May 2017 @evanm Software at Whisker Labs Framing the narrative 

May 2017 @evanm Software at Whisker Labs Lesson 1: Mind your Ps and Qs A good way to contextualize these tiers of software is to consider their time scales. 

May 2017 @evanm Software at Whisker Labs Lesson 1: Mind your Ps and Qs Component Sensing element Sensor buffer Transmitter Applications Sample/ request rate ~2 kHz 10 Hz O(1) Hz - Time scale ~500 μs 100 ms O(1) s O(1)–O(1×106) 

May 2017 @evanm Software at Whisker Labs Lesson 1: Mind your Ps and Qs Fig. 2—A ring buffer. 

May 2017 @evanm Software at Whisker Labs Lesson 1: Mind your Ps and Qs When independent components have to talk to each other, it’s critical to get the protocols right. 

May 2017 @evanm Software at Whisker Labs Lesson 1: Mind your Ps and Qs t i v p 1493586051474 1.05 119.6 125.58 1493586052483 1.11 119.6 132.756 1493586053530 1.10 119.4 131.34 1493586054300 1.09 119.5 130.255 1493586055712 1.03 119.9 123.497 1493586056802 1.06 120.1 127.306 

May 2017 @evanm Software at Whisker Labs Lesson 1: Mind your Ps and Qs Fig. 3—Cycles of waveform data overlaid atop each other. Read more at bit.ly/adavg. 

May 2017 @evanm Software at Whisker Labs Lesson 2: Conservatism Production-grade embedded development requires a level of conservatism not fashionable in popular software culture. 

May 2017 @evanm Software at Whisker Labs Lesson 2: Conservatism 

May 2017 @evanm Software at Whisker Labs Lesson 2: Conservatism Low-hanging fruit: testing & QA 

May 2017 @evanm Software at Whisker Labs Lesson 2: Conservatism Low-hanging fruit: testing & QA To limit risk from externalities, it pays to conservative. 

May 2017 @evanm Software at Whisker Labs Lesson 3: Everything old is new again The techniques in IoT aren’t new. They just haven’t been relevant to the typical programmer for decades. 

May 2017 @evanm Software at Whisker Labs Lesson 3: Everything old is new again Fig. 4—Photo of Marvin Minsky working on an IoT product 

May 2017 @evanm Software at Whisker Labs Closing To summarize, there is no default path for a connected device company. 

May 2017 @evanm Software at Whisker Labs Evan Meagher @evanm on Twitter [email protected] PS: we’re hiring whiskerlabs.com/about.html Questions?