1J.O. KLEIN JOK@IEF.U-PSUD.FR

Institut Universitaire de Technologie de CACHANUniversité PARIS SUD - FRANCE

An Introduction to Real Time Operating System

with UCOS-II

www.micrium.com

Jean Labrosse

Portable

Royalty Free

Readable Source

Simple

Well Suited for MCU

Well documented

2

Background / InterruptModel Limitation

INT

Background

Loop …

TimeBCKGND

INT 1

ISR

ISR

ISRINT

INT

INT 0

ISR < 100 us

ISR > 1 ms Latency

ISR 0

INT 1-Pending

3

RTOS-Solution

ISR1

TimeIDLE

INT 1

INT 0

Task 1

ISR0

ISR1

Task 1

Task 1

ISR0

4

Practical Timing Ranges

RTOS Tick = Time unit for delay & timeout

1 us 1 ms 1 s

ISR

RT-Tasks

ProcessingTime

BackGnd-Tasks

T

5

UC/OS-II RTOS ObjectsSystem

ISR

INT

INTISR

INT

Task 0

T60

Ticks

ISR

T 10

Semaphore

T63IDLE

MessageQueue

Tx-FIFO

Mailbox

Timer INT

T61

T30

MemoryBuffers

6

Simple Tasksvoid myTask (void*pdata){

while (TRUE){…

OSTimeDly(ticks);}

}

TaskTicks

Task

Task

void myTask (void*pdata){while (TRUE){

…OS???Pend(ticks);}

}

??? := Sem | Mbox | Q

7

Polling & scheduling

while ((PTH & 8)==0){}

Task

Task

PORTH [3]

while ((PTH & 8)==0){OSTimeDly(1);

}

No context switching :Lower tasks are waiting

Context switching :Lower tasks can run

8

Interrupt Service Routine

interrupt VECTOR_NUMvoid myISR (void){

OSIntEnter();……OSIntExit();

}

OSIntNesting++

ISR

if (OSIntNesting-- == 0){…OSIntCtxSw();

}

Task 10

Task 5

ISRINT

Preemption

9

RT Ticks & Timer Interrupt

ISR

RT Timer

1 ms

OSTimeTick

Ticks

OSTimeDly(tick)

OS???Pend( event, tick, &err)

10

Semaphore

ISR Task

Task

Initial Value = 1

Initial Value = 0

if(mySem=OSSemCreate(InitialVal) != NULL)…

err=OSSemPost(mySem)

OS_EVENT*mySem

OSSemPend(mySem,tick, &err)

OptionalTimeout

tick:

11

Mail Box

Task

if (myMbox=OSMboxCreate(NULL)) != NULL)…

OptionalTimeout

err=OSMboxPost( myMbox,TxMessage)

RxMessage = OSMboxPend(myMBox,tick,&err)

OS_EVENT*myMbox

void*TxMessage

tick:

void*RxMessage

12

Message Queue

Task

If (myQ = OSQCreate(Buffer,N)) != NULL)…

…OSQPost(myQ,TxMsg)

RxMsg=OSQPend(myQ, ticks,&err)

OS_EVENT*myQ

…OSQPostFront(myQ,TxMsg)

…OSQFlush(myQ)

void*TxMsg

void*Buffer[N]

OptionalTimeout

tick:

void*RxMsg

err =…

13

Memory Buffer

If (myMem=OSMemCreate(buf,N,blksize,&err) != NULL)…

OSMemPut(myMem,&err)

OS_MEM*myMem

Buffer

TaskNO

TimeoutNo

wait

Buffer

OSMemGet(myMem,&err)

INT8U buf[N*blksize]

14

Code Architecture

XXX.C

XXX.H

XXX_EVENTS_INIT

MYTASK_CREATE

MYTASK

MAIN.C ALL_INCLUDES.H

Task

MAIN

INIT

StartRTOS.CSTAR12_Init

APP_Task_CREATE

RTOS_Checking

ALL_Events_Init

(HardwareConfiguration)

15

Creating a Task

err = OSTaskCreateExt (myTask, pdata, ptos, prio, id, pbos, MYTASK_stk_size, pext, opt);

Task

void myTask (void*pdata);static OS_STK MYTASK_stack[MYTASK_stk_size];void * ptos =

(void*)&MYTASK_stack[MYTASK_stk_size-1];void * pbos = (void*)&MYTASK_stack[0];INT8U prio = … ; // 0(higher) to 63(idle)INT8U id = 0; // unusedINT16U opt = OS_TASK_OPT_STK_CHK |

OS_TASK_OPT_STK_CLR; void*pdata = NULL; //optional data ptr void*pext = NULL; // optional ptr

16

XXX.H

Code Generator

XXX.C

XXX_EVENTS_INIT

MYTASK_CREATE

MYTASK

17

Training Course

Introduction to RTOS Multitasking,

Scheduling Task States Preemptive/

Cooperative Task Stacks

Introduction to uCOSII Task, Semaphore,

Mbox,Q,Mem Starting the OS Code Architecture Code Generator

Getting Start Load the demo Add a commented task Debug !

Writing an Application Use Code Generator Adding the Files to

project Adding the task to the

App. Debug

1H30

Lecture Labs

1H00

2H00

3H00

ISR Task 0

18

Starsky

1 LineControl

2 MotorControl

3 LineSensor (I2C)

4 USSensor

5 Monitor (RS232)

6 Function

Application Tasks

60 RS232

61 LCD

62 Init (+RTOS Checking)

63 Idle

Service & System Tasks

19

Monitoring5 Monitor

60 RS232

62 Init (+RTOS Checking) CPU Usage

Stack Usage Delay 1s

Wait for RS232 Q

Constitute Frames

Copy msg to TxFIFO

Enable SCI Tx ISR

Send Sensors & Variables values through RS232

Print To LCD buffer

Delay 100 ms

61 LCD Copy LCD buffer

to LCD controller

Delay 100 ms

20

Application Starsky1 LineControl

2 MotorControl

Wait for MotorCtrlSem

Read Speed PI Controller or Open

loop Setting PWM Values

4 USSensor

Emit Ultrasound Delay 5ms Sample echo Delay 30 ms

3 LineSensor

Read line position /I2C

Delay 1 ms

Wait for LineCtrlSem ShortCut & Crossing

Detection End Detection Line Tracking

6 Function (Main Task)Select Mode (Stop,demo,normal…)Delay (variable)Set Motor Order or post LineCtrlSem

5 Monitor

Emit variable values via RS232 & LCD

Delay 100 ms

/

21

HC12 Enhanced Capture Timer

Free running Timer

Timer Capture Register

Timer CaptureHolding Register

Pulse Accumulator

Pulse AccumulatorHolding Register

PA Overflow

Read ICHReg

16

8

Frequency = Periodic PA sampling

Period =

TC - TCH

22

Frequency = Periodic PA sampling

Period =

TC - TCH

The choice

Frequency Measurement

UINT16 ECT_MOTOR_PT1_speed ( void ){ UINT16 Speed, Delta; Delta = (TC1 - TC1H); TotalPa1 += PA1H ; Speed_mm_per_sec = DiffPA1 * 21; return ( (Speed> 100) ?

(3272490UL / Delta) : Speed);}

Modulus Down Counter

5 ms

MotorCtrlSem

MotorControl

ISR

1/10

50 msvoid ECT_MOTOR_update(void) { Delta_ic1 = (TC1 - TC1H); // Tfer PA -> PAH Delta_ic3 = (TC3 - TC3H); // Tfer PA -> PAH TotalPa1 += PA1H; TotalPa3 += PA3H; DiffPA1 = TotalPa1 - TotalPa1_old; DiffPA3 = TotalPa3 - TotalPa3_old; TotalPa1_old = TotalPa1; TotalPa3_old = TotalPa3;}

23

Starsky Project• Professor

– STAR 12 Board design 3 months– STAR12 Software Lib 2 months– UCOS-II Port to STAR12 Board 1 month– UCOS-II/Star12 Service 1 month

• 20 Students group– Frequency, Motor controller,

H-bridge, RS232 Monitor, I2C 6 weeks– All together, Line tracking 6 weeks

• 3 students – Starsky & Hutch design 8 weeks