Andrew Caples

Sr. Product Marketing Manager, Nucleus RTOS

SmartGrid: Power Aware Embedded

Devices for the Modern Age

Agenda Introduction: What is Smart Grid?

What’s out there today?

The Smart Grid Challenge

Meeting SEP 2.0 requirements in Embedded Systems

Choosing the right Hardware

Choosing the right Software

Software Architecture

What is Smart Grid?

Introduction

Energy Company Electric Meter

Appliance

In-Home Display

Internet

Smart Meter

Smart Appliance

Thermostat

Storage

Energy Company

In-Home Display

Internet

Smart Meter

Smart Appliance

Storage

Smart Grid – Home Area Network

Inefficient

Aging

Dumb

World-wide problem

Energy Grid problems

Make the grid “Smart”

Government forcing standards

Need to comply with standards

Keep the costs down

Challenges faced by manufacturers

Few or limited Standards

Complying to Standards: Not a problem !

Devices do not and are not required to

contribute to the grid’s intelligence

Energy and Communication flow is uni-

directional.

What’s out there today?

Zigbee Alliance working on SEP 2.0

Devices require SEP 2.0 compliance

Lots of requirements:

TCP/UDP, IPv6, HTTP(s), Network Time Protocol (NTP)

Wireless (WiFi, ZigBee, etc.)

Connectivity (Serial/USB for servicing functions like firmware download)

Security

and more ……

Flow of Communication must be bi-directional

Provide full-featured support AND keep BOM minimal

Cost increase is not acceptable

The Smart Grid challenge

SPI

SPI

Meeting SEP 2.0 Requirements

No particular hardware specification

Link Layer agnostic

The right hardware:

Minimize power consumption

Need for SEP 2.0 compliance should not increase

the size of the device itself

Enhanced hardware technology should have

minimal impact on cost

Hence the need for low cost 32-bit MCU

SPI

Choosing Embedded Hardware

Power Management Modes

Chip Mode Chip Mode

Normal Run LLS (Low Leakage Stop)

Normal Wait- via WFI VLLS3 (Very Low Leakage Stop3)

Normal Stop- via WFI VLLS2 (Very Low Leakage Stop2)

VLPR (Very Low Power Run)

VLLS1 (Very Low Leakage Stop1)

VLPR (Very Low Power Wait) – via WFI

BAT (backup battery only)

Rich TCP/UDP stack with full IPv6 support

HTTP(s) support

RESTful architecture

XML or EXI encoding support

Network Time Protocol support

SSL/TLS support for Security

Zero Configuration Networking

Power Management

Support a bunch of standard predefined function sets

SPI

Choosing Embedded Software

Options

× Linux won’t fit on an MCU

× Bare metal software likely insufficient

× In-house s/w development is expensive

• Using COTS reduces product dev time and per unit

costs

Real Time Operating Systems: Yes!!

• Example:

SPI

Software Choices

RTOS

Software Architecture

Microcontroller (MCU)

Board support package

Smart Energy Profile (SEP) API

Application

TCP/IP (fully featured)

Real Time Kernel

Power Manager

Security

)(

Operating System and BSP

App

= Hardware power management

= RTOS Power Mgmt Framework

= Application Software

1616

Nucleus Power Management

Device Manager Watchdog Service

Idle Scheduler

DVFS Service

Peripheral State Service

System State

Service

Nucleus Kernel

Hardware Agnostic

Nucleus BSP

Hardware Specific

Nucleus Power Management APIs

CPU Idle & CPU

Wakeup Functions

CPU State Driver

Per

iphe

ral

Driv

er

Per

iphe

ral

Driv

er Peripheral Driver

Per

iphe

ral D

river

w

ith H

iber

nat

e

Per

iphe

ral D

river

w

ith H

iber

nat

e

Hibernate & Standby OPs

Peripheral Driver with Hibernate

17Nucleus 3rd Generation

17

Code Comparison

17

Nucleus

Bare Metal RTOS Power Aware RTOS0

5000

10000

15000

20000

25000System Lines of Code (SLOC)

Example: power optimized networking application

• Task scheduling

• Hardware abstraction (driver interface)

• Empty idle task

• BSP / drivers

• Power aware BSP/drivers

• Optimized idle task

• Automatic tick suppression

• DVFS aware OS and BSP/drivers

• System state and DFVS operating point management abstraction

Nucleus

1818

System State / Peripheral State Control

System State Serial Touch Display Ethernet

SS_ACTIVE ON ON BRIGHT ON

SS_IDLE1 ON ON ON ON

SS_IDLE2 ON ON DIM OFF

SS_STANDBY1 ON ON OFF OFF

SS_STANDBY2 ON OFF OFF OFF

19Nucleus 3rd GenerationMentor Graphics Confidential Information1919

Power Management Example

19

static VOID PMF_Task_Entry(UNSIGNED argc, VOID *argv){

PM_STATUS pm_status; 

while (1){ pm_status = NU_PM_Set_Current_OP(eMHZ_400);

pm_status = NU_PM_Set_System_State(eLCD_ON_USBH_ON);NU_Sleep(1*NU_PLUS_TICKS_PER_SEC);

  pm_status = NU_PM_Set_System_State(eLCD_DIM_USBH_ON);NU_Sleep(1*NU_PLUS_TICKS_PER_SEC);

pm_status = NU_PM_Set_System_State(eLCD_OFF_USBH_ON);NU_Sleep(1*NU_PLUS_TICKS_PER_SEC);

  pm_status = NU_PM_Set_System_State(eLCD_OFF_USBH_OFF);NU_Sleep(1*NU_PLUS_TICKS_PER_SEC);

  pm_status = NU_PM_Set_Current_OP(eMHZ_133);NU_Sleep(1*NU_PLUS_TICKS_PER_SEC);

}}

2020

Power Consumption at Various OPs

SOC Current Consumption(mA)

(ARM9 SOC)

Operating Point voltage (1.5V)

470

370

230

200

OP#3 454 MHz

OP#2 297 MHz

OP#1 63 MHz

OP#0 1 MHz

38Standby

0Hibernate

0 100 200 300 400 500

20

Goals for Smart Grid: Consumer participation

Zigbee Alliance coming up with SEP 2.0

Avoid driving the costs up

Use of 32bit MCUs

Use of RTOS

Conclusion