Atmel | SMART Reference Design Smart Plug Technical Presentation MCU + Wireless + Security + Sensing

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The three pillars of the IOT The fundamentals of an IOT Edge Node

Software 2

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Connectivity

Intelligence

Security

IOT Node • • • • • • •

Low Power Connected Small Secure Scalable Inexpensive Robust

What Does it Take to Make IoT a Reality? Integrating IoT Technologies The core of any IoT design will incorporate an embedded processing device, potentially one or more sensors, connectivity that typically will be wireless-based, and finally, and possibly most importantly, device security.

The core component of the Software / Development Tools Ecosystem for IoT is Atmel START.

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A Real IoT Application – Smart Plug Application scenarios

• •

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Power plug with Wi-Fi, which enables power on/off control through Mobile App. A typical IoT device and can be integrated into all kinds of cloud based IoT platform

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Introducing the Atmel Smart Plug Built on the three pillars of the IOT • • • • • • • • •

Turnkey system reference design CE/FCC & UL(CUL) certified US, EU and Chinese Outlet standards available AC Input from 90-265VAC @ 50Hz or 60Hz Maximum output of 10 Amps WiFi Connectivity Industry leading power measurement Touch User interface Cloud Connectivity

• (default) Cloudless, only with Android App • JingDong Smart Cloud (source code only) • Proximetry Cloud (source code only) •

Smart Phone provisioning and control

• Smart Plug Android App in Google Play • JD Weilian App (Android/iOS) 6

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Smart Plug System Overview Block Diagram

ATSAMW25-MR510PB

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Smart Plug Deliverables Orderable kits 1. Ordering Code

• ATSMARTPLUG-US • ATSMARTPLUG-EU • ATSMARTPLUG-CN

3. Atmel Store: http://www.atmel.com/tools/smart-plug-reference-design.aspx#buy

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Smart Plug Deliverables Application notes/Hardware design files/Firmware 1. Application Notes

• • • • • •

Atmel AT15736: Atmel Smart Plug Getting Started Guide Atmel AT16225: Atmel Smart Plug Hardware User Guide Atmel AT15735: Atmel Smart Plug Firmware User Guide AT16268: JD Smart Cloud Based Smart Plug Getting Started Guide AT16267 - Firmware User Guide on JD Cloud Service Integration with Smart Plug AT17284 – Proximetry Cloud Based Smart Plug User Guide

2. Hardware design files released as .zip pack attached to AT16225 3. Default cloudless firmware on ASF3

• Used in certification, • Pre-programmed • Source and binary released as .zip pack attached to AT15735

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Smart Plug Deliverables Firmware examples in Start 1. Three firmware examples in Atmel Start (available)

• Cloudless FW on ASF4 through Atmel START • JD Smart Cloud based firmware through Atmel START • Proximetry Cloud based firmware through Atmel START 2. Re-Programming is required to run these examples

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Smart Plug Deliverables Mobile App 1. Mobile App available

• Smart Plug Android APP (v1.2.2) in Google Play •

Work with cloudless FW and Proximetry Cloud FW

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https://play.google.com/store/apps/details?id=net.nanmu.atmel.smartplug

• JD WeiLian App (only in Chinese language) • Work with JD Smart Cloud based FW • http://smartcloud.jd.com/app

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The Atmel Smart Plug

Hardware Design

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Smart Plug Design Highlight Hardware Design

• • • • • •

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Three variants, each compliant with power outlet standards: US/EU/China Share the same circuit design and PCB layout Three PCB boards

• MCU board • Power board • Touch board Small and only cover the size of the wall-plug Safety protection CE/FCC and UL compliance

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US

EU

China

Hardware Block Diagram Hardware Design

Output Socket

E N Input Plug

L

Relay

Fuse

ATM90E26 DC/DC 12V

WINC1500 3.3V SAMD21

LEDs

ECC508

Button

AC/DC

DataFlash

ATSAMW25

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MCU Board Hardware Design

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MCU Board

• • • •

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SAMW25 32K crystal Data flash (Reserved) Programming Interface

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MCU Board Hardware Design

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Schematic For SAMW25

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Smart Plug Design Highlight Hardware Design

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Interface Definition

• SWD interface • 1.27mm 10-pin

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SWD header pin

Pin definition

ATSAMW25 pin

1

SWDCLK

25

2

GND

3

NC

4

VCC

5

SWDIO

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6

RESET

24

7

NC

8

NC

9

NC

10

NC

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Power Board Hardware Design

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Power Board

• AC-DC (220VAC-12VDC) • DC-DC (12V-3.3V) • Power Measurement • •

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(M90E26) Relay Plug and Socket

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Smart Plug Design Highlight Hardware Design

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Schematic For Power Measurement Sample and Relay Control

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Power Board Hardware Design

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Schematic For AC-DC

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Power Board Hardware Design

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Schematic For Power Measurement

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Smart Plug Design Highlight Hardware Design

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Power Measurement Design consideration

• AT90E26 is a professional single phase •

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power metering IC. The parameter GL, Ugain, Igain and PLconstant come from the calculation, and can be modified in code.

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Smart Plug Design Highlight Hardware Design

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Interface Definition

• Header to Power Board • Soldered

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Power header pin

Pin definition

1

VCC

2

GND

3

Wi-Fi TXD (Reserved for Wi-Fi firmware upgrade on fixture)

2

4

Wi-Fi RXD (Reserved for Wi-Fi firmware upgrade on fixture)

3

5

Test RXD (Reserved for fixture)

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6

Test TXD (Reserved for fixture)

18 41

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Power Measurement RXD (Interface for MCU and power measurement device) Power Measurement TXD (Interface for MCU and power measurement device)

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8 9

MCU Reset (Reserved for fixture)

24

10

Relay Control

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MCU SWDIO (Reserved for fixture)

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12

MCU SWDCLK (Reserved for fixture)

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ATSAMW25 pin

Smart Plug Design Highlight Hardware Design

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Touch Board

• Touch Pads • LEDs

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Except the Touch Key which handles the ON/OFF/Reset function, another 2 touch sensors act as the touch guard. The touch guard sensors will prevent some scenarios from spurious triggering

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Touch Board Hardware Design

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Schematic For Touch Board

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Touch Board Hardware Design

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PCB Design For Touch Pads

• The square in the middle is the • •

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ON/OFF touch pad. The 2 ‘L’ pads are the guard pad. They are designed as the selfcapacitance sensors.

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Smart Plug Design Highlight Hardware Design

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Interface Definition

• Header to Touch Board • Plug-in, detachable

Touch header pin

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Pin definition

ATSAMW25 pin

1

GND (External power input while the onboard power is not available)

2

VCC (External power input while the onboard power is not available)

3

Touch Guide Sensor 1

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4

Power LED Green

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5

Touch Key Sensor

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6

Power LED Red

27

7

Touch Guide Sensor 2

35

8

Wi-Fi LED Red

14

9

Wi-Fi LED Yellow

16

10

Wi-Fi LED Green

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PCB Stack Structure Hardware Design

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PCB Stack Structure

• Power Board is the mother board • •

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of the Kit. MCU board is soldered/mounted on the power board directly. Touch Board is assembled inner surface of top case. It connect the MCU board via connector.

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Smart Plug Design Highlight Hardware Design

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Power consumption distribution

Status

Power consumption

Standby

0.4W max

Communicating

1.3W max

Communicating while Relay on

1.8W max

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Smart Plug Design Highlight Hardware Design

• •

CE/FCC, UL compliance UL consideration

• All components/materials are UL

• • •

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compliance. The distance between the AC part and DC part should be bigger than 6mm The thickness of case is bigger than 2mm. etc.

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Smart Plug Design Highlight Hardware Design

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Programming Tools

• JTAG with SWD interface which • •

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supported by most of the Atmel Tools. 1.27mm, 10-pin header AVR programming port

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Smart Plug Design Highlight Hardware Design

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Reprogramming Procedure

• Remove the Silica and screws • • •

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in the case. Open the case Connect the external 3.3V to the touch header Connect the cable to the MCU board

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Smart Plug Design Highlight Hardware Design

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Reprogramming the SAMW25

• Follow the regular programming process to re-program the SAMW25

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Smart Plug Design Highlight Hardware Design

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HW Limitation when reprogramming

• The user can not debug the touch code since the touch board is • •

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removed. The Relay is not powered, so it will not work even the control signal is active. The external 3.3V only powers the SAMW25 but the AC part, the Power Measurement will not work.

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The Atmel Smart Plug

Firmware Design (Cloudless Version)

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Smart Plug Design Highlight Firmware Design - Functionality

• • • • • • • • • • •

On/Off control by phone APP Touch button control Programmable 7-day/week schedules (day/hour/minute) Output Energy/Voltage/Current/Power measurement Device temperature monitor and alarm Connection status indication (online/offline) Historic record of output energy/status etc. One-step Wi-Fi configuration to provision new smart plug Share Smart Plug to multiple users Smart Plug firmware OTAU Security

• Data Encryption/Decryption • Message Integration • Node Authentication

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Smart Plug Design Highlight Firmware Design - FW Architecture

• •

The pre-programmed FW is based on ASF 3.x No RTOS Application

Initialization

UI - Touch Button, - LED

Wi-Fi Connectivity

Security Initialization

Protocol and Control Logical

Atmel Software Framework Services, Components, Drivers

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Sensor -Energy Measurement -Temperature

Smart Plug Design Highlight Firmware Design – Atmel Start Configuration Page

• • •

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Atmel Start version available. Based on ASF 4 Application layer is the same.

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Smart Plug Design Highlight Firmware Design – MCU peripherals used

MCU ATSAMD21 Timer & Counter

GPIO

PTC

LED Indicator & Relay

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RTC

Emulated EEPROM

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EIC

ADC

Calendar mode

Temperature reference

SERCOM

SERCOM

SERCOM

SPI

I2C

UART

Wi-Fi

Security

Energy Measurement

ATWINC1500

ATECC508A

AT90E26

Touch Button

Smart Plug Design Highlight Firmware Design – Memory map & Flow chart 0x00040000

EEPROM 0x0003C000

Emulated EEPROM to store:    

Wi-Fi SSID, PWD; User ID, keys; Application area info; Recent historic log, etc.

Application 2

Application area:    

0x00020000

Divided into two areas; Only one application area is valid at a time; OTAU will update the other application area; All functions run from application area.

Application 1

Bootloader: 0x00004000

Bootloader 0x00000000

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 Check for valid application area by reading EEPROM;  Boot from valid application area;  No Wi-Fi and other application layer functions.

Smart Plug Design Highlight Firmware Design – Memory map & Flow chart 0x00040000

EEPROM

Power on reset

0x0003C000

No

Bootloader

Application 2

0x00020000

Application area found?

OTAU

Yes

Application firmware

Application 1 No OTAU triggered and completed? 0x00004000

Yes

Bootloader 0x00000000

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Read Boot info from EEPROM

Warm reset

Smart Plug Design Highlight Firmware Design – Project folder structure

Protocol clusters and commands Plug node type function implementation SEGGER Real Time Transfer codes used for debug purpose

Atmel CryptoAuthentication support library Third party crypto library

MCU internal temperature sensor reading

QTouch button handler

Crypto functions based on ATECC508A LED indicator control Metering AFE initialization and control Main files

Wi-Fi application code

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Smart Plug Design Highlight Firmware Design – Project folder structure (Atmel START)

CryptoAuthentication middleware Smart Plug application layer code (Similar to ASF3 based project) Qtouch library and EEPROM emulation are added separately as part of the application layer code.

Atmel START generated folders/files STDIO redirect middleware ATWINC1500 Wi-Fi middleware

Atmel START generated code.

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Smart Plug Design Highlight Firmware Design – Touch Button

• • • •

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ATSAMD21 PTC (Peripheral Touch Controller) is used for the touch button. Self-cap method. PTC QTouch Library is from ASF. Totally three sensors are used:

• One sensor for the button. • Two sensors as guard sensors to avoid false touch. As RTC is used in calendar mode, the timer for touch detection is from a separate TC.

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Smart Plug Design Highlight Firmware Design – Wi-Fi Connectivity

• • • •

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SERCOM is configured as SPI to work with ATWINC1500 inside ATSAMW25 module. Wi-Fi host driver is from ASF. By default, ATSAMW25 works in AP mode to allow Android app to provision the smart plug. After provisioned, smart plug will switch to STA mode and connects to Wi-Fi router for further communication with Android app.

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Smart Plug Design Highlight Firmware Design – Wi-Fi Connectivity

• •

Adding New Device Working Session: node control, OTAU, node sharing etc.

Smart Provision

Node in AP mode WiFi Node Discovery WiFi Node Discovery Response APP

Add new node

Query attribute Report attribute

Query attribute Report attribute

Node in STA mode Data Exchange Control attribute

APP

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Wi-Fi Router

Report attribute

Smart Plug Design Highlight Firmware Design – Wi-Fi Connectivity

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OTAU flow – Upgrade the host MCU firmware over the air Each time OTAU is done, the application area will be switched to new firmware. OTAU state cmd (OTA_HOST) OTAU state cmd response (OK) Smart plug switching to OTAU mode OTAU data frame 0 OTAU data frame response (OK) OTAU host MCU in progress

APP

Wi-Fi Router

OTAU data frame n OTAU data frame response (OK) OTAU state cmd (CRC_HOST) CRC check of host MCU in progress OTAU state cmd response (OK) OTAU state cmd (RUN_NEWF) OTAU state cmd response (OK)

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Smart plug

Smart Plug Design Highlight Firmware Design – Protocol between plug and Android app

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Two types of command frame formats

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•

•

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Non-encrypted:

Encrypted:

SOF

Data length

Seq. Num

CMD ID

Reserved

Command Payload

CRC32

Uint8

Uint16

Uint8

Uint8

Uint32

Variable

Uint32

0x5A

Packet length

SOF

Data length

Encrypted data

Initial Vector

ECDH Public Key

CRC32

Uint8

Uint16

N x 16 bytes

16 bytes

64 bytes

Uint32

0x5B

Packet length

Data to be encrypted: Nonencrypted command frame + MAC

Node public key used for ECDH

Include SOF

Defined commands

Supported commands

• • • • •

Network Entry Command Node Authentication Command Query Command Control Command Report Command

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by

specific

Include SOF

Smart Plug Design Highlight Firmware Design – Energy Measurement

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• •

An external metering AFE (ATM90E26) is used for energy measurement. The following data is measured in smart plug:

• • • •

Current – instant RMS current Voltage – instant RMS voltage Power – instant active power Electrical energy – accumulated electrical energy

More parameters can be read from ATM90E26 if required. Refer to ATM90E26 datasheet for details. SERCOM is configured as UART to work with ATM90E26.

• 9600 • 1 stop bit • No parity

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Smart Plug Design Highlight Firmware Design – Temperature Measurement

• • •

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The ADC internal temperature reference is used for temperature measurement. The actual temperature is calculated based on method in chapter “Temperature Sensor Characteristics” of ATSAMD21 datasheet. The purpose of temperature measurement is to provide a rough and low cost temperature warning function.

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Smart Plug Design Highlight Firmware Design – Memory footprint

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Flash usage：

• 83244 bytes, 31.8% Full

Data 10 256

RTT 268

Crypto 9 676

ASF+gcc lib 23 580

Sensor 1 748

Protocol&Logic 10 656

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SRAM usage：

Wi-Fi 16 072

Touch&LED 10 380

• 15632 bytes, 47.7% Full

RTT 1 160

ASF + gcc lib 556

Sensor 169 Wi-Fi 1 966 Touch&LED 1 290

Stack size 8 192 53

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Crypto 894 Protocol&Logic 2 009

Smart Plug Design Highlight Security - Overview

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Crypto Features

• Hardware-based Key Storage • High-Speed Public Key Algorithms • ECDSA: FIPS186-3 Elliptic Curve Digital Signature Algorithm • ECDH: FIPS SP800-56A Elliptic Curve Diffie-Hellman Algorithm

• • • •

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AES-128 session key from ECDH key agreement algorithm Session key changes session by session. Message Integration by SHA-256 Node Authentication by ECDSA

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Smart Plug Design Highlight Security - Prerequisites

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For Node Authentication, two key/signature pairs are generated by/programmed into ECC508A in factory.

• Pub-d= Device Public Key • Priv-d= Device Private Key (Can never be read out) - To sign random

• • •

• • •

challenge from host. Sig-d= Device Signature by Signer (Priv-s) Pub-s= Signer Public Key Sig-s= Signer Signature by Root (Priv-root)

One public key is stored to phone APP.

• Pub-root= Root Public Key from Root Authority For ECDH, a key pair are generated by/preprogrammed in ECC508A in factory.

• Pub-x= ECDH eXchange Public Key • Priv-x= ECDH eXchange Private Key (Can never be read out) One key pair are generated on APP.

• Pub-host= Host Public Key from Android • Priv-host= Host Private Key from Android 55

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Smart Plug Design Highlight Security - Adding node

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Node Authentication – Verify smart plug 1) The Root Public Key (Pub-root) has been loaded onto the APP

APP

Smart Plug

New Smart Plug is started in AP mode 2) The APP has an ECC key pair (Priv-host & Pubhost)

APP selects one Smart Plug to connect to Request Device Authentication packet Device Authentication packet = Pub-d + Sig-d + Pub-s + Sig-s Verify Device Cert - ECDSA(sha2-Pub-d, Sig-d, Pub-s)

Not verified Show error Authenticity

Verify Signer Cert - ECDSA(sha2-Pub-s, Sig-s, Pub-root) Device verified Send Random Challenge: (randNum1) authSig = Sign(sha2-randomNum1, Priv-d) Random Challenge Response: authSig

Not verified Show error

Verify Device - ECDSA(sha2-randNum1, authSig, Pub-d) Send Android Public Key: (Pub-host) ACK

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Smart Plug Design Highlight Security - Adding node Cont..

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Encryption & Integrity

• Get device ID or

other device secret

APP

Smart Plug

Request DevInfoPacket Read Pub-x preMasterKey = ECDH(Priv-x, Pub-host) sessionKey = MAC(randNum1, preMasterKey) IV = Random() Collect data: DevInfo DevMac = MAC(DevInfo, preMasterKey)

Confidentiality DevInfoValid = DevInfo + DevMac DevInfoEnc = AES(DevInfoValid, sessionKey, IV) DevInfoPacket = DevInfoEnc + IV + Pub-x Reply with DevInfoPacket preMasterKey = ECDH(Priv-host, Pub-x) sessionKey = MAC(randNum1, preMasterKey) Decrypt = AES(DevInfoEnc, sessionKey, IV)

DevMacCalc != DevMac Show error Integrity 57

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DevMacCalc = MAC(DevInfo, preMasterKey) DevMacCalc == DevMac

Smart Plug Design Highlight Security – Working session

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Node Authentication – Verify user

The APP has an ECC key pair (Priv-host & Pubhost)

APP

Smart Plug

Both APP and Smart Plug connect to the same Router Wi-Fi Node Discovery Random Challenge with node MAC adddr: (randNum2) + MAC addr authSig = Sign(sha2-randNum2, Priv-host) Random Challenge Resp with host/user random: authSig + host/user random Authenticity Verify user - ECDSA(sha2-randNum2, authSig, Pub-host) User verified

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Not verified Drop request

Smart Plug Design Highlight Security – Working session Cont..

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Encryption & Integrity

APP

Smart Plug

• Data Exchange User verified Read Pub-x preMasterKey = ECDH(Priv-x, Pub-host) sessionKey = MAC(randNum2, preMasterKey) IV = Random() Collect data: DevData DevDataMac = MAC(DevData, preMasterKey) DevDataValid = DevData + DevDataMac DevDataEnc = AES(DevDataValid, sessionKey, IV) DevDataPacket = DevDataEnc + IV + Pub-x Reply with DevDataPacket preMasterKey = ECDH(Priv-host, Pub-x) Confidentiality

DevMacCalc != DevMac Show error

sessionKey = MAC(randNum2, preMasterKey) Decrypt = AES(DevDataEnc, sessionKey, IV) DevMacCalc = MAC(DevData, preMasterKey)

Integrity DevMacCalc == DevDataMac --- Show device in APP Session established

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Encrypted Wi-Fi Node Discovery resp

Smart Plug Design Highlight Security - Node Sharing

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•

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Crypto Requirement

• • • •

Node Authentication – Verify Original User Node Authentication – Verify Shared User Get device ID or other device secret – Encryption and Integrity Only original user could delete shared user

Crypto flow is similar to the those mentioned during adding node and working session.

© 2015 Atmel Corporation

© 2015 Atmel Corporation. Atmel®, Atmel logo and combinations thereof, Enabling Unlimited Possibilities®, and others are registered trademarks or trademarks of Atmel Corporation or its subsidiaries. Other terms and product names may be trademarks of others. Disclaimer: The information in this document is provided in connection with Atmel products. No license, express or implied, by estoppel or otherwise, to any intellectual property right is granted by this document or in connection with the sale of Atmel products. EXCEPT AS SET FORTH IN THE ATMEL TERMS AND CONDITIONS OF SALES LOCATED ON THE ATMEL WEBSITE, ATMEL ASSUMES NO LIABILITY WHATSOEVER AND DISCLAIMS ANY EXPRESS, IMPLIED OR STATUTORY WARRANTY RELATING TO ITS PRODUCTS INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT. IN NO EVENT SHALL ATMEL BE LIABLE FOR ANY DIRECT, INDIRECT, CONSEQUENTIAL, PUNITIVE, SPECIAL OR INCIDENTAL DAMAGES (INCLUDING, WITHOUT LIMITATION, DAMAGES FOR LOSS AND PROFITS, BUSINESS INTERRUPTION, OR LOSS OF INFORMATION) ARISING OUT OF THE USE OR INABILITY TO USE THIS DOCUMENT, EVEN IF ATMEL HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. Atmel makes no representations or warranties with respect to the accuracy or completeness of the contents of this document and reserves the right to make changes to specifications and products descriptions at any time without notice. Atmel does not make any commitment to update the information contained herein. Unless specifically provided otherwise, Atmel products are not suitable for, and shall not be used in, automotive applications. Atmel products are not intended, authorized, or warranted for use as components in applications intended to support or sustain life.

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