1 Stellaris® Robotic Evaluation Board and Micriµm µC/OS-III Dexter Travis, Stellaris ARM® Cortex™-M3 Applications Engineering Jean J. Labrosse, Founder,

1

Stellaris® Robotic Evaluation Board and Micriµm µC/OS-III

Dexter Travis, Stellaris ARM® Cortex™-M3 Applications Engineering

Jean J. Labrosse, Founder, President and CEO of Micriµm

Introductions

•Jean J. Labrosse –Founder, President and CEO of Micriµm

•Dexter Travis–Stellaris® ARM® Cortex™-M3 Applications Engineering

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Find the right ARM® Solution for you

32-bit ARMCortex™-M3

MCUs

DSPDSP+ARM

ARM Cortex-A8 &

ARM9™ MPUs

Stellaris®

ARM Cortex-M3

Sitara™

ARM Cortex-A8& ARM9

C6000™

DaVinci™

Digital Media processors

Integra™

Up to 80 MHz

Flash8 KB to 256 KB

USB, ENET MAC+PHY CAN, ADC, PWM, SPI

Connectivity,Security,Motion Control, HMI,Industrial Automation

$1.00 to $8.00

32-bit ARM MCU for

Safety-Critical Applications

TMS570ARM

Cortex-R4™

Up to 250 DMIPS/ 160 MHz

2 MB Flash, 160 KB RAM

FPU, ECC, Timer/PWM Co-Proc, 12bit ADCs, CAN,

EMIF, LIN, SPI, Flexray

Transportation, Motor Control, Certified for use in safety critical (SIL3) systems

$7.00 to $18.00

375MHz to >1GHz

Cache, RAM, ROM

USB, CAN, SATA,SPI, PCIe, EMAC

Industrial automation, POS & portable

data terminals

$5.00 to $25.00

300MHz to >1Ghz +Accelerator

Cache RAM, ROM

USB, ENET, PCIe, SATA, SPI

Floating/Fixed PointVideo, Audio, Voice,

Security, Conferencing $5.00 to $200.00

Comprehensive developer ecosystemS

oftw

are

supp

ort

Developm

ent tools

Responsive design support

Agenda

• RTOSs and Real-Time Kernels– A brief introduction

• Micriµm - µC/OS-III– Summary of features

– Scheduling and Context Switching

– Synchronization

– Message Passing

– Other Services

• Texas Instruments - EVALBOT– Features

– Examples

– Demo

© 2010, Micriµm, All Rights Reserved© 2010, Micriµm, All Rights Reserved www.Micrium.comwww.Micrium.com

Displaywith optional

Touch Interface

DisplayController

Touch ScreenController

GraphicalUser

Interface

FileSystem

MediaController

Media(SD)

(MMC)(NAND Flash)(NOR Flash)

(CF)(RAM Disk)

Other

AudioI2S

Controller

KeyboardKeyboardController

CPU

Timer

InterruptController

Real-TimeKernel

EthernetController(MAC/PHY)

TCP/IPStack

USB(Host)

(Device)

USBStacks

CANController

CAN

RS-232CRS-485

Modbus

Other(Shell)(Clk)

(CRC)(etc.)

TCP/IPApps

Application

RTOS

RTOS vs Real-Time KernelsRTOS vs Real-Time Kernels


What is a Real-Time Kernel?What is a Real-Time Kernel?

Software that manages the time of a CPU Performs multitasking

– ‘Switches’ the CPU between tasks– Highest priority task runs on the CPU– Round-robins tasks of equal priority

Provides valuable services to an application:– Task management– Synchronization– Mutual exclusion management– Message passing– Memory management– Time management– Soft-timer management– Other


What is a Real-Time Kernel?What is a Real-Time Kernel?

Task

Event Event

Each Task

Infinite Loop

Task

High Priority Task

Low Priority Task

Task

Task

Task

Task

Task

Importance Task Task


ISR

Low-priority task

High-priority task

ISR

Preemptive KernelsPreemptive Kernels

Interrupt occurs

ISR completes and the kernel switches to the high-priority task

© 2009, Micriµm, All Rights Reserved www.Micrium.com

Via a kernel call, the ISR makes the high priority task ready

The kernel switches to the low-priority task

Time


What is µC/OS-III?What is µC/OS-III?

A third generation Real-Time Kernel– Has roots in µC/OS-II, the world’s most popular Real-Time Kernel

µC/OS-II’s internals were described in the book: “MicroC/OS-II, The Real-Time Kernel” (1998)

A new 850+ page book:– “µC/OS-III, The Real-Time Kernel”– Describes µC/OS-III’s internals– The book comes with:

A Cortex-M3 based evaluation board– Featuring TI’s LM3S9B92

Links to download:– Sample code to run µC/OS-III– IAR’s 32K KickStart tools– A trial version of µC/Probe

– Companion EVALBOT 5 Example projects


µC/OS-IIISummary of Key FeaturesµC/OS-IIISummary of Key Features

Preemptive Multitasking– Round-robin scheduling of equal-priority tasks

ROMable Scalable

– Adjustable footprint

– Compile-time and run-time configurable

Portable– All µC/OS-II ports can be adapted to µC/OS-III

Rich set of services– Task Management, Time Management, Semaphores, Mutexes, Message

Queues, Soft Timers, Memory Management, Event Flags and more


µC/OS-IIISummary of Key FeaturesµC/OS-IIISummary of Key Features

Real-Time, Deterministic– Reduced interrupt and task latency

Built-in Performance Measurement– Measures interrupt disable time on a per-task basis

– Measures stack usage for each task

– Keeps track of the number of context switches for each task

– Measures the ISR-to-Task and Task-to-Task response time

– And more

Cleanest source code in the industry Consistent API Run-Time argument checking


void MyTask (void *p_arg){ Do something with ‘argument’ p_arg; Task initialization; for (;;) { Wait for event; /* Time to expire ... */ /* Signal/Msg from ISR ... */ /* Signal/Msg from task ... */ /* Processing (Your Code) */ }}

Typical µC/OS-III TasksTypical µC/OS-III Tasks

Task(Priority)

Stack(RAM)

CPURegisters

VariablesArrays

Structures

I/ODevices

(Optional)


You create a task by calling a service provided by the kernel:

OSTaskCreate(OS_TCB *p_tcb, CPU_CHAR *p_name, OS_TASK_PTR p_task, void *p_arg, OS_PRIO prio, CPU_STK *p_stk_base, CPU_STK *p_stk_limit, OS_STK_SIZE stk_size, OS_MSG_QTY q_size, OS_TICK time_slice, void *p_ext, OS_OPT opt, OS_ERR *p_err);

‘Creating’ a Task‘Creating’ a Task

Task Control Block

Task Name

Task Start Address

Priority

Stack

Stack Size

Stack Limit

Time Slice

Options


The µC/OS-III Scheduler Using Count Leading Zeros (CLZ)The µC/OS-III Scheduler Using Count Leading Zeros (CLZ)

The Cortex-M3 has a CLZ instruction– Makes scheduling much faster … ex. with 64 priorities

0 0 0 0 0 0 00 0 0 0 0 0 0 00

310

0 0 0 0 1 1 00 1 1 1 0 1 1 11

[0]

[1]

32

5

Ready Priority = 37

32 63

if (ReadyTbl[0] == 0) Prio = CLZ(ReadyTbl[1]) + 32;else Prio = CLZ(ReadyTbl[0]);

#Zeros

ReadyTbl[]


The µC/OS-III Ready ListThe µC/OS-III Ready List

EntriesTail

Head

ReadyList[MAX_PRIO]

1Tail

Head

EntriesTail

Head

EntriesTail

Head

EntriesTail

Head

EntriesTail

Head

EntriesTail

Head

[MAX_PRIO-1]

[4]

[3]

[2]

[1]

[0]

[5]

Prev Next

- Other Fields -

Prev Next

- Other Fields -

Prev Next

- Other Fields -

Prev Next

- Other Fields -

0

0

00

0

0

00

00

00

00

Idle Task's TCB

TCBTCB

TCB

Highest Priority

Lowest Priority

Multiple TasksAt

Same Priority


Context SwitchARM Cortex-M3 for µC/OS-IIIContext SwitchARM Cortex-M3 for µC/OS-III

(1): Current task’s CPU registers are saved on current task’s stack

(2): CPU’s SP register is saved in current task’s TCB

(3): New task’s SP is restored from the new task’s TCB

(4): CPU registers are restored from the new task’s stack


Resource Management(Mutual Exclusion Semaphore)Resource Management(Mutual Exclusion Semaphore)

Delta TS


Synchronization(Semaphores)Synchronization(Semaphores)

Delta TS


Synchronization(Event Flags)Synchronization(Event Flags)

Delta TS


Message Passing(Message Queues)Message Passing(Message Queues)

Delta TS


Other µC/OS-III FeaturesOther µC/OS-III Features

Task Management– Suspend/Resume a task

– Delete a task

Time Management

Software Timers

Fixed-Size Memory Partitions

Pending on Multiple Objects

And more.


µC/Probe


What is µC/Probe?What is µC/Probe?

‘Windows’ application to display/change target data:– ANY variable– ANY memory location– ANY I/O port

Works with ANY processor– 8-, 16-, 32-, 64-bit or DSP

Works with ANY compiler– Compiler/linker needs to generate an ELF/DWARF file such as Embedded

Workbench Supports many interfaces

– RS-232C– USB– TCP/IP (Ethernet)– J-Link– SWD (Cortex-M3) … NO target resident coded needed!– Others

Target doesn’t need an RTOS– Works with or without an RTOS


µC/ProbeµC/OS-III Task AwarenessµC/ProbeµC/OS-III Task Awareness

Task Name

Task Priority

% CPUUsage

Max Interrupt Disable Time

Stack Usage

ISR to TaskResponse

ISR to TaskResponse

#ContextSwitches

To run the book examples … you will need:

• The µC/OS-III book

• The TI EVALBOT– http://www.ti.com/evalbot

• Download and install the IAR 32K edition of Embedded Workbench for the ARM (V5.5)– http://supp.iar.com/Download/SW/?item=EWARM-KS32– You will need to install the J-Link driver

• Download and unzip the µC/OS-III book examples:– http://www.Micrium.com/Books/Micrium-uCOS-III

• Download and install the non-time limited TRIAL version of µC/Probe:– http://www.Micrium.com/Books/Micrium-uCOS-III

Texas Instruments EVALBOT unassembled

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Texas Instruments EVALBOT

Bumpers(2)

96x6 OLEDDisplay

Motor/Wheel(2) Batteries

(3 AA)

ON/OFFSwitch

User Switches(2)

StellarisLM3S9B92

MicroSDSocket

RJ45 10/100Ethernet

USB-DeviceConnector

USB-HostConnector

In-CircuitDebug Interface

Speaker

Examples

• Example 1: Simple Display– Rotates a series of messages on the Display

– Blinks LEDS on the board

• Example 2: Using Audio– Bump sensors select next or previous wav track

– SWITCH2 begins audio playback, SWITCH1 stops playback

• Example 3: Simple Control– Manual start/stop of the motor via SWITCH1, SWITCH2 and bump sensors

• Example 4: Autonomous Control– EVALBOT moves randomly and reacts to sensor inputs.

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Autonomous EVALBOT Control

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Input Monitor Task posts flags to Control Task

Control Task queues commands to motor tasks

If Timer expires a random turn is initiated

Motor Tasks receives command, interprets and

posts to PID Task

PID Task closes motor control loop based on feedback from speed

sensor interrupt handlers

speed sensor interrupts relay data back to PID Task

buttons and Bump Sensor trigger Input monitor task

Documents

1 Stellaris® Robotic Evaluation Board and Micriµm µC/OS-III Dexter Travis, Stellaris ARM® Cortex™-M3 Applications Engineering Jean J. Labrosse, Founder,