# 😴 Wakeup! #### Continuous monitoring on #### on low power devices <span style="font-size: 0.7em;">Chinmay Pendharkar, 2019</span>

## 👋🏾 About Me - NUS ECE alumni (2006) - Embedded systems / Audio - Organize monthly meetup (Hackware) - CTO at Subnero

## Subnero <img style="width: 100px; vertical-align: bottom;" src="imgs/subnero.png"> - NUS spin-off (2013) - At The Hangar, I-Cube (_Come say Hi!_) - Underwater communications and networks - In-water sensing and monitoring solution

### Underwater Acoustic Modems <img style="width: 30%; vertical-align: middle; padding-right: 20%" src="imgs/venus7.jpg"> <img style="width: 25%; vertical-align: middle;" src="imgs/deployment.jpg">

### Inside <img style="width: 30%; vertical-align: middle; padding-right: 10%" src="imgs/electronics.jpg"> <img style="width: 40%; vertical-align: middle;" src="imgs/code.png">

Acoustic Wakeup

• Normal Mode 🏃‍♂️

• Low Power Mode 🛌

• A "wakeup signal" 📢

#### 🤔 Acoustic Wakeup.. #### where have I seen that before??

### Voice Activation - Power Modes - Run Mode 🏃‍♂️ - Normal use mode - High power usage - User interaction (Screen On) - User control to change to Sleep Mode - Sleep Mode 🛌 - Battery conservation mode - Low power usage - Minimal/no user interaction (Screen Off) - A "wakeup signal" to change to Run Mode 📢

### What's inside a phone?📲

### What's inside a phone?📲

iPhone 8 Teardown

iFixit

iPhone 8 Circuit Board

iFixit

### Sooo... how does this work? 🤷‍♂️

Openmoko Neo Freerunner

Openmoko

### Openmoko Power Consumption Battery Capacity: 4400 mWh | Mode | Power | <span class="fragment" data-fragment-index="1"> Duration</span> | | -------------- | --------- | -------- | | Phone Call | 1054 mW | <span class="fragment" data-fragment-index="1"> 4 h</span> | | Video Playback | 454 mW | <span class="fragment" data-fragment-index="1"> 10 h</span> | | Web Browsing | 429 mW | <span class="fragment" data-fragment-index="1"> 10 h</span> | | <span class="ht">Run 🏃‍♂️</span> | <span class="ht">269 mW</span> | <span class="fragment ht" data-fragment-index="1" class="ht">16 h</span> | | <span class="ht">Sleep 🛌</span> | <span class="ht">69 mW</span> | <span class="fragment ht" data-fragment-index="1" class="ht">64 h</span> | <span style="font-size: 0.5em;"><a href="https://www.usenix.org/legacy/event/atc10/tech/full_papers/Carroll.pdf">Openmoko Neo Freerunner</a></span>

To have any decent battery life, devices **must** go into **Suspend** mode ASAP!😴

### SoC Power Modes  <span style="font-size: 0.5em"><a href="http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0388f/Chdejjdj.html">ARM9 TRM</a></span>

### Sooo... how to wake up a sleeping phone?? 🤔

"External wake-up event required to wake up."

→ an interrupt pin has to be toggled by something else

### How to toggle an interrupt pin? - Button 🖲 - "Hey Siri" 📢

xkcd 208

### Microcontrollers (<span style="text-transform: none">µC</span>) 🎯 - Low power 🔋 - Can run software ⌨️ - Built-in peripherals 🛠

### LPC1769 <p style="margin: 0px"><img src="imgs/lpc-power.png"></p> <span style="font-size: 0.5em;"><a href="https://www.nxp.com/products/processors-and-microcontrollers/arm-based-processors-and-mcus/lpc-cortex-m-mcus/lpc1700-cortex-m3/512kb-flash-64kb-sram-ethernet-usb-lqfp100-package:LPC1769FBD100">LPC1769 datasheet</a></span>

### LPC1769 - Power | Mode | Power | | --------------- | -------------- | | <span class="ht">Active (12MHz)</span> | <span class="ht">23 mW</span> | | Active (100MHz) | 138 mW | | Sleep | 7 mW | | Deep Sleep | 1 mW |

### Algorithm - Continuously "listen" → 🎤 - Detect "trigger words" → [🤖](https://machinelearning.apple.com/2017/10/01/hey-siri.html) - Toggle a pin → 📌

### Listening to Audio - Microphone 🎤 (Analog) - Analog → Digital Converter (ADC) - Audio Data 💽 (Digital)

### LPC1769 - Peripherals <div style="display: flex; justify-content: space-around; align-items: center;"> <p style="margin: 0px; width: 48%"><img src="imgs/lpc-block.png"></p> <span style="font-size: 0.5em;"><a href="https://www.nxp.com/products/processors-and-microcontrollers/arm-based-processors-and-mcus/lpc-cortex-m-mcus/lpc1700-cortex-m3/512kb-flash-64kb-sram-ethernet-usb-lqfp100-package:LPC1769FBD100">LPC1769 datasheet</a></span> </div>

### Continuous Monitoring Setup <p style="margin: 0px;"><img style="width: 80%" src="imgs/lp.jpg"></p>

### Sleep Mode 🛌 <p style="margin: 0px;"><img style="width: 80%" src="imgs/lp-sleep.jpg"></p>

### Run Mode🏃‍♂️ <p style="margin: 0px;"><img style="width: 80%" src="imgs/lp-wake.jpg"></p>

### Continuous Monitoring Power | Mode | SoC | µC | Total | Duration | | ------- | ------ |------ |------- |----------| | Run 🏃‍♂️ | 269 mW | 1 mW | 270 mW | <span class="ht">16 h</span> | | Sleep 🛌| 69 mW | 23 mW | 92 mW | <span class="ht">48 h</span> |

### How to reduce power even more ?🔋 - NXP KL03 Low Power µC <p style="margin: 0px;"><img style="width: 80%" src="imgs/kl03.png"></p> <span style="font-size: 0.5em;"><a href="https://www.nxp.com/docs/en/data-sheet/KL03P24M48SF0.pdf">KL03 datasheet</a></span>

### How to reduce power even more ?🔋 <br> - Disable un-needed µC peripherals - Turn on µC 10% of the time (10 ms ON, 90 ms OFF)

### How to reduce power even more ?🔋 <p style="margin: 0px;"><img style="width: 60%" src="imgs/bela.png"></p> <span style="font-size: 0.5em;"><a href="https://www.nxp.com/docs/en/data-sheet/KL03P24M48SF0.pdf">BELASIGNA R281 datasheet</a></span>

### How to reduce power even more ?🔋 <p style="margin: 0px;"><img style="width: 50%" src="imgs/a11.jpg"></p> <span style="font-size: 0.5em;"><a href="https://en.wikipedia.org/wiki/Apple_A11#/media/File:Apple_A11.jpg">By Henriok - Own work</a></span>

### Where else is this applicable?🔋 - Wearables (fitness bands, step counters) - Smart watches⌚️ - Smart Cars 🚙 - Anything "Smart" + battery operated

### What did we learn today ? 📚 - SoCs and µC have various power modes - Simple power calculations - Put to sleep parts of systems to conserve power - Battery life vs functionality trade-off

# Questions ? .. thoughts, ideas, wonderings ... ? <br> <br> <span style="font-size: 0.5em;">http://chinmay.audio/talks</span>