training.micrium.ucos-ii.rtos

Industrial Reference Design PlatformMicrium µC/OS-II RTOS

Release 1.0

TSC Americas – IRD Platform – Micrium uC/OC-II RTOS

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Products without KernelsForeground/Background Systems

Background

Foreground #1

Foreground #2

Time

Task #1 Task #2 Task #3

Infinite loop

ISR #1 ISR #1

ISR #2


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Foreground/BackgroundDisadvantages – Response Time

Background response time is the background execution time– Non-deterministic

• Affected by if, for, while ...

– May not be responsive enough– Changes as you change your code


Infinite loop

ISR

Task #4

Poll to see if ISR occurred

Affected by if, for, while


Infinite loop

ISR

Task #4

Poll to see if ISR occurred

Affected by if, for, while


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Foreground?/Background TasksDisadvantages - Priority

All ‘tasks’/functions() have the same priority– Code executes in sequence– If an important event occurs, it’s handled at the same priority as everything

else– May need to execute the same code often to avoid missing an event


Infinite loop

Task #4Task #1 Task #2 Task #3

Infinite loop

Task #4


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What is an RTOS?

Real-Time Operating System– Software that manages the time of a microprocessor,

microcontroller, or a digital signal processor– Prioritizes the work to be done– Provides ‘multitasking’– Provides ‘services’ to the application

• Semaphores• Message mailboxes and queues• Event flags• Time delays, timers, and timeouts• Task management• Memory management• Bandwidth assessment ‘idle time’


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Types of RTOSs

1. Pre-emptive:Always runs the highest available task. Tasks of identical priority share CPU time (fully pre-emptive with round robin time slicing)

2 . Cooperative:Context switches only occur if a task blocks, or explicitly relinquishes CPU control


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RTOS Advantages

Software that manages the time of a microprocessor or microcontroller

– Ensures that the most important code runs first

Allows Multitasking– Do more than one thing at the same time– Application is broken down into multiple tasks, each handling one aspect of

your application– It’s like having multiple CPUs

Provides valuable services to your application– Time delays– Resource sharing– Inter-task communication and synchronization


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Available RTOSs for LPC2300/2400A few of those available

Keil RTX Real-Time Kernel

– http://www.keil.com/arm/rl-arm/kernel.asp

Micrium µC/OS-II

– http://www.micrium.com/products/rtos/kernel/rtos.html

CMX-RTX

– http://www.cmx.com/rtx.htm

Express Logic ThreadX

– http://www.rtos.com/

Segger ebmOS

– http://www.segger.com/embos_general.html

uClinux

– As distributed with the EA LPC2468 board

FreeRTOS.org

– http://www.freertos.org/


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Why NXP chose Micrium µC/OS-IIFor the LPC2468 Industrial Reference Design (IRD) Platform

Written in ANSI C– Source code provided– Consistent coding style

Pre-emptive

Deterministic

Royalty-free– Licensed on a per-end-product basis

Extensive Documentation and Support

Meets requirements of Safety-Critical Systems

Large user base– Used in hundreds of products all over the world


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Micrium µC/OS-IIFeature Set

Full suite of modules in addition to the Operating System (RTOS)– µC/FS: File System– µC/Probe: Run-Time Monitoring– µC/TCP-IP: Networking Protocol– uC/HTTPs: HTTP Server– µC/GUI: Graphics User Interface– µC/USB: Universal Serial Bus

• Host: Mass Storage, HID, Communication Device Class (CDC)• Device: Bulk, Mass Storage, HID, CDC

– µC/CAN: Controller Area Network– µC/FL: Flash Loader– µC/LCD: VFD

Small Footprint

Scaleable


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Micrium µC/OS-II and Related Files

CPUSpecific(Port)

CPUIndependent

BoardSupportPackage


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Micrium µC/OS-II on the LPC2468 IRDModules we use

TCP-IP Protocol StackIncludes: IPv4, ARP, ICMP, UDP, TCP, BSD 4.4, and HTTPs

Real-Time Operating System (RTOS)Manage up to 255 tasks

Host USB Stack (Host Controller Driver for OHCI)Mass Storage Host Class driver enabled

USB Core( Core Device module needed for all applications)HID Class driver enabled, LPC24xx Target Device

CAN framework API ( abstracts CAN messages and signals)RX/TX CAN communication, LPC24xx Target Device

Run-Time data monitor Supports RS-232, TCP/IP, USB, JTAG

µC/Shell and µC/LCD usedLCD/VFD character based display driver

Microsoft compatible FAT File SystemBasic Package, MCU RAM disk driver included


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Module Flash size RAM

BSP 8503 32

uC/LCD 384 6

App tasks 8697 4133

uC/USB Host 26565 10669

uC/USB Device 7410 513

uC/LIB 19744 228

uC/OS 8898 7584

uC/HTTP 4236 6696

uC/TCP-IP 77634 24531

uC/CAN 5892 2428

uC/Probe 1392 1070

uC/FS 17124 565

uC/Shell 10996 4240

Total 197475 62695

Micrium µC/OS-II on the LPC2468 IRDMicrocontroller Resource Allocation


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Micrium µC/OS-II on the LPC2468 IRDTask Priorities

Task Name Priority Function

AppTaskStart()"Start Task" 1 Starts the Application Tasks

AppTaskKbd()"Keyboard" 2Reads status of push buttons; passes IDs of pressed buttons to AppTaskStart() in a queue.

HC_AsyncIOHandler "USBH AsynC" 4 USB Host Controller Asynchornous IO handler

OSProbe_Task "Probe TCP/IP" 5 µC/Probe Task

Terminal_OS_Task ""Terminal" 6 Terminal Task

"Net IF Rx Task" 7The task in which µC/TCP-IP receives data from a NIC or EMAC driver.

"Net Timer Task" 8 The task used by µC/TCP-IP to manage its timers.

"HTTP Server" 9 µC/HTTPs (Web Server)

"USBH MSC Demo" 10 Mass Storage Device Task

"USD device HID" 17 USB Device HID

"Echo CAN" 25 µC/CAN Echo task

AppTaskHeartbeat "HeartBeat" 28 Generates a 1Hz signal in the heartbeat pin

"uC/OS-II Tmr" 29 Manages µC/OS-II timers

"uC/OS-II Stat" 30 Collect stack usage statistics

"uC/OS-II Idle" 31 Executes when no other task is executing


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Micrium µC/OS-II on the LPC2468 IRDPricing

TCP-IP Protocol StackIncludes: IPv4, ARP, ICMP, UDP, TCP, BSD 4.4, and HTTPs $11,500.00

Real-Time Operating System (RTOS)Manage up to 254 application tasks $4,995.00

Host USB Stack (Host Controller Driver for OHCI)Mass Storage Host Class driver enabled $9,750.00

USB Core( Core Device module needed for all applications)HID Class driver enabled, LPC24xx Target Device $4,700.00

CAN framework API ( abstracts CAN messages and signals)RX/TX CAN communication, LPC24xx Target Device $2,350.00

Run-Time data monitor Supports RS-232, TCP/IP, USB, JTAG $995.00

µC/Shell and µC/LCD usedLCD/VFD character based display driver $2,000.00

Microsoft compatible FAT File SystemBasic Package, MCU RAM disk driver included $3,750.00


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Micrium µC/OS-II on the LPC2468 IRD Built upon the µC/OS-II Foundation

uC/LCD was ported for the Noritake VFD

uC/CAN was ported for the LPC23xx/24xx CAN controller

I2C Keypad Decoding was created

I2CTemperature Driver was created

I2C LED Blinker and Buttons driver was created

Piezo driver was created

Heartbeat task was created

Demonstration web pages for IRD components

BSP was ported from the Embedded Artists - LPC2468 base board to the IRD base board


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RTOS Tasks

A task is a simple program that thinks it has the CPU all to itself

Each Task has– Its own stack space– A priority based on its importance

A task contains YOUR application code


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What is a Task?

A task is an infinite loop

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


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Designing with µC/OS-IISplitting an application into Tasks

High Priority Task

Low Priority Task

Task

Task

Task

Task

Task

Task

Event Event

Each Task

Infinite Loop

Importance


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µC/OS-II Task States

TasksReside

InROM

Task Waiting For Event

TaskReady-To-Run


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Why ‘Create’ a Task?

To make it ready for multitasking

The kernel needs to have information about your task– Its starting address– Its top-of-stack (TOS)– Its priority– Arguments passed to the task– Other information about your task


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Creating a task with µC/OS-II

OSTaskCreateExt(void (*task)(void *parg), void *parg, OS_STK *pstk, INT8U prio, INT16U id, OS_STK *pbos, INT32U stk_size, void *pext, INT16U opt);


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Initializing µC/OS-IIExecution Path

main

Disable Interrupts

Start the execution of the RTOS

Create the First Application Task (AppTaskStart)

Initialize internal OS structures

Disable Interrupts

Initialize:interrupt nesting countertask countercontext switch counterstatistics TCB and Events lists


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Initializing µC/OS-IIFirst Application Task

No

Initialize the HW (BSP_Init)

Initialize TCP/IP

Initialize CAN

Initialize USB Host

Initialize USB Device

Start

Create the Application Tasks

Execute the AppTaskStart infinite task code


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IRD Micrium µC/OS-II Exercise

Create a new task called “AppTaskHeartbeat”

This task will generate a 0.5 Hz square wave signal– Displayed by the Heartbeat LED (P2.30)


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IRD Micrium µC/OS-II ExerciseSteps

1. Open the IAR project workspace

2. Insert the initialization of the Heartbeat pin (P2.30) in the bsp.c file

3. Insert the body of the “AppTaskHeartbeat” task in the app_heartbeat.c file

4. Insert the AppTaskHeartbeat protoytpe in the file app.c

5. Insert the function call “OSTaskCreateExt” to create the task in the “AppTaskStart” function in the app.c file

6. Define the AppTaskHeartbeat stack in the app.c file

7. Define the AppTaskHeartbeat priority and stack size in the app_cfg.h file

8. Compile and run the projectThese steps are covered in detail in

the upcoming slides


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IRD Micrium µC/OS-II Exercise Project files

Please make sure that IAR version 4.42A4.42A is installed in your system– The project has only been tested in this version

• Newer IAR releases changed the linker configuration– the code won’t compile in the latest IAR version available on their web site

Uncompress the IRD project file in a directory close to the root directory

– Note: IAR won’t find some files if the PATH is too big


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Exercise – Step 1Open IAR Micrium µC/OS-II project workspace

Project Name– LPC2468-IRD-OS-Probe-TCPIP-VFD.ewwLPC2468-IRD-OS-Probe-TCPIP-VFD.eww


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Exercise – Step 2Prepare to configure P2.30 as an output

Open the bsp.c file and find the function GPIO_Init()


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Exercise - Step 2Configure the P2.30 as an output

Add the following code at the end of the function

pinsel = PINSEL5;

pinsel &= 0xCFFFFFFF;

PINSEL5 = pinsel;

FIO2DIR |= DEF_BIT_30;


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Exercise - Step 3Create the AppTaskHeartbeat function

Open file app_heartbeat.c and find the comment

/*Insert the AppTaskHeartBeat here */


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Exercise - Step 3Create the AppTaskHeartbeat function

• An infinite loop is needed for all the tasks

• P2.30 is being toggled

• A 1 second delay is executed after modifying the pin voltage level

• Function OSTimeDlyHMSM generates the delay

void AppTaskHeartbeat(void *p_arg){

(void)p_arg;

while (DEF_TRUE) {

if( FIO2PIN & DEF_BIT_30){

FIO2CLR = DEF_BIT_30;

}else{

FIO2SET = DEF_BIT_30;

}

OSTimeDlyHMSM(0, 0, 1, 0);

}

}

Please insert the following code after the comment


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Open file app.c and find the comment

/*Insert the AppTaskHeartbeat prototype here */

Exercise - Step 4Prepare to Insert the AppTaskHeartbeat Prototype


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Exercise - Step 4Insert the AppTaskHeartbeat Prototype

Copy the following code line

extern void AppTaskHeartbeat (void *p_arg);


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Open file app.c and find the comment

/*Insert the OSTaskCreateExt call here */

Exercise - Step 5Prepare to create the AppTaskHeartbeat task


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Exercise - Step 5AppTaskHeartbeat creation

The function AppTaskCreateAppTaskCreate creates the application tasks

Add the following code at the end of the function AppTaskCreateAppTaskCreate (app.c file)

OSTaskCreateExt(AppTaskHeartbeat,

(void *)0,

(OS_STK *) &AppTaskHeartbeatStk[APP_TASK_HEARTBEAT_STK_SIZE - 1],

APP_TASK_HEARTBEAT_PRIO,

APP_TASK_HEARTBEAT_PRIO,

(OS_STK *)&AppTaskHeartbeatStk[0],

APP_TASK_HEARTBEAT_STK_SIZE,

(void *)0,

OS_TASK_OPT_STK_CHK | OS_TASK_OPT_STK_CLR);

#if (OS_TASK_NAME_SIZE > 9)

OSTaskNameSet(APP_TASK_HEARTBEAT_PRIO, (CPU_CHAR *)"Heartbeat", &err);

#endif


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Exercise - Step 6Prepare to define the AppTaskHeartbeat Stack

Find the following comment in the app.c file

/*Insert the AppTaskHeartbeat stack definition*/


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Exercise - Step 6AppTaskHeartbeat Stack definition

Copy the following code line

static OS_STK AppTaskHeartbeatStk[APP_TASK_HEARTBEAT_STK_SIZE];


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Exercise - Step 7Prepare to define stack size and priority

• Find the following comments in the app_cfg.h file

/*Insert the AppHeartbeat Task Priority*/

/*Insert the AppHeartbeat Stack Size*/


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Exercise - Step 7Define Stack size and priority• The following constants need to be defined at this point:

#define APP_TASK_HEARTBEAT_STK_SIZE 96

#define APP_TASK_HEARTBEAT_PRIO (OS_LOWEST_PRIO - 3)

Note:The OS_LOWEST_PRIO is 31 in µC/OS-II


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Exercise – Step 8Compile the project

Compile as per screenshot


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Exercise – Step 8Run the project

Start debugger– Run project

You should see a the Heartbeat LED blinking at a 0.5 Hz rate


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