Software Development with an Open Source RTOS

Renesas Electronics America Inc.
© 2012 Renesas Electronics America Inc. All rights reserved.
Software Development with an
Open Source RTOS
© 2012 Renesas Electronics America Inc. All rights reserved.2
Renesas Technology & Solution Portfolio
© 2012 Renesas Electronics America Inc. All rights reserved.3
Microcontroller and Microprocessor Line-up
Wide Format LCDs
 Industrial & Automotive, 130nm
 350µA/MHz, 1µA standby
44 DMIPS, True Low Power
Embedded Security, ASSP
165 DMIPS, FPU, DSC
1200 DMIPS, Performance
1200 DMIPS, Superscalar
500 DMIPS, Low Power
165 DMIPS, FPU, DSC
25 DMIPS, Low Power
10 DMIPS, Capacitive Touch
 Industrial & Automotive, 150nm
 190µA/MHz, 0.3µA standby
 Industrial, 90nm
 242µA/MHz, 0.2µA standby
 Automotive & Industrial, 90nm
 600µA/MHz, 1.5µA standby
 Automotive & Industrial, 65nm
 600µA/MHz, 1.5µA standby
 Automotive, 40nm
 500µA/MHz, 35µA deep standby
 Industrial, 40nm

 242µA/MHz, 0.2µA standby
 Industrial, 90nm
 1mA/MHz, 100µA standby
 Industrial & Automotive, 130nm
 144µA/MHz, 0.2µA standby
2010
2013
32-bit8/16-bit
© 2012 Renesas Electronics America Inc. All rights reserved.4
Microcontroller and Microprocessor Line-up
Wide Format LCDs
 Industrial & Automotive, 130nm
 350µA/MHz, 1µA standby
44 DMIPS, True Low Power
Embedded Security, ASSP
165 DMIPS, FPU, DSC
1200 DMIPS, Performance
1200 DMIPS, Superscalar
500 DMIPS, Low Power
165 DMIPS, FPU, DSC
25 DMIPS, Low Power
10 DMIPS, Capacitive Touch
 Industrial & Automotive, 150nm
 190µA/MHz, 0.3µA standby
 Industrial, 90nm
 242µA/MHz, 0.2µA standby
 Automotive & Industrial, 90nm
 600µA/MHz, 1.5µA standby
 Automotive & Industrial, 65nm
 600µA/MHz, 1.5µA standby

 Automotive, 40nm
 500µA/MHz, 35µA deep standby
 Industrial, 40nm
 242µA/MHz, 0.2µA standby
 Industrial, 90nm
 1mA/MHz, 100µA standby
 Industrial & Automotive, 130nm
 144µA/MHz, 0.2µA standby
2010
2013
32-bit8/16-bit
32-Bit High Performance
DSP, FPU with High Integration
© 2012 Renesas Electronics America Inc. All rights reserved.5
‘Enabling The Smart Society’
DVR
Game Console
Smart Phones
Navigation
Systems
Music Players
Tablet PC
© 2012 Renesas Electronics America Inc. All rights reserved.6
Agenda
 Definitions
 Why RTOS?
 Why FreeRTOS?
 Lab Exercises
 Questions


Feedback Form
© 2012 Renesas Electronics America Inc. All rights reserved.7
Definitions, RTOS, and FreeRTOS
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What is Your RTOS Experience?
 I have previously used an RTOS in a commercial product
 I am using an RTOS in my current project
 I am considering using an RTOS in the near future and
would like to get as much info as possible
 I am a “Super-Loop” user and here to burn you down
© 2012 Renesas Electronics America Inc. All rights reserved.9
Some Definitions
 REAL-TIME: Computing with a deadline
 Hard real-time (Air bag)
 Soft real-time (Adaptive volume)
 TASK: Self contained code that handles a singular
functionality or semi-independent portion of an application
 Process
 Thread
 SCHEDULER: Implements the scheduling policy
 Kernel
 Operating system (OS)
 PRIORTY: Used in arbitration mechanism
© 2012 Renesas Electronics America Inc. All rights reserved.10
Why Use an RTOS? (1 of 2)
 Abstracting timing information
 Kernel is responsible for system time
 Modularity
 Tasks are independent modules with well defined purpose
 Team development

 Designers can work on different tasks simultaneously
 Code reuse
 Modules allow code re-use with less effort
 Improved efficiency
 Event driven software
 Code executes only when it is needed
© 2012 Renesas Electronics America Inc. All rights reserved.11
Why Use an RTOS? (2 of 2)
 Flexible interrupt handling
 Short interrupt routines that detects events
 Most of the work deferred to a task
 Mixed processing requirements
 Periodic execution
 Continuous functions
 Event driven processing
 Real-time requirement ordering with priorities
 Control over peripherals
 Shared resources
 Gatekeeper tasks
© 2012 Renesas Electronics America Inc. All rights reserved.12
Why FreeRTOS?
 Widely used and known
 Open source
 Simple and easy to port
 Feature rich but small size
 Free use and distribute
 Path to commercial versions
 OpenRTOS: Full support, additional components
 SafeRTOS: Functional safety, IEC 61508 compliant
 More on FreeRTOS site

 /> />© 2012 Renesas Electronics America Inc. All rights reserved.13
What is our role with FreeRTOS?
 Port FreeRTOS to Renesas MCUs
 Work with FreeRTOS to qualify ports
 Provide sample projects with FreeRTOS
 Direct Drive LCD
 Firmware Integration Technology (FIT)
 Support by FreeRTOS
 Partner with other RTOS vendors for full support
 Micrium: uc/OS
 Segger: embOS
 CMX: CMX-RTX
© 2012 Renesas Electronics America Inc. All rights reserved.14
Lab Exercises
© 2012 Renesas Electronics America Inc. All rights reserved.15
General Notes on Lab Exercises
 Refer to lab handout
 Total of 6 lab exercises
 Short description up
front
 About 10-minute labs
 Recap at end
 LEDs show running task
LED5 Task1
LED6 Task2
LED7 Task3
LED8 Task 4
LED9 Run time stats
LED10 Idle Task
© 2012 Renesas Electronics America Inc. All rights reserved.16

Lab Exercise 1 - Tasks, Priorities, Task States
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Lab Exercise 1 - Tasks, Priorities, Task States
 APIs: xTaskCreate(),
vTaskDelay(),
vTaskDelayUntil(),
vTaskStartScheduler()
 Pre-emptive scheduling
 Highest priority ready task
 Time slice same priority
tasks
 Idle task
 Low priority background or
continuous tasks
 Spare processing time
 System in low power
 MUST NOT BLOCK!
Suspended
Ready
Blocked
Running
vTaskSuspend()
vTaskSuspend() vTaskResume()
vTaskSuspend()
Event
Blocking API function
© 2012 Renesas Electronics America Inc. All rights reserved.18
Lab Exercise 1 – You can start the lab now
© 2012 Renesas Electronics America Inc. All rights reserved.19
Lab Exercise 1 – Recap (1 of 3)

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Lab Exercise 1 – Recap (2 of 3)
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Lab Exercise 1 – Recap (3 of 3)
 Hard real time -> Higher priority
 Soft real time -> Lower priority
 Execution times

Processor utilization
 Rate Monotonic Scheduling (RMS)
 Unique priority based on the periodic execution rate
 The higher periodic execution the higher the priority
 Better scheduling of tasks
 Not all tasks are periodic
 Execution times must be considered
© 2012 Renesas Electronics America Inc. All rights reserved.22
Lab Exercise 2 – Queue Management
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Lab Exercise 2 – Queue Management
 APIs: xQueueCreate(),
xQueueSendToBack(),
xQueueSendToFront(),
xQueueReceive(),
uxQueueMessagesWaiting()
 Communication between tasks
and interrupts
 Blocking API call
 Not owned by a particular task
 Any task can write to a queue
 Any task can read from a

queue
 Byte by byte copy of the data
Tail
Head
Tail
Head
20
Send
20
Tail
Head
2010
Send
10
Tail
10
Head
Receive
20
© 2012 Renesas Electronics America Inc. All rights reserved.24
Lab Exercise 2 – More on Queues
 Use pointers for large data
 Pointers queued
 Some rules must be followed
 Clearly define the owner of
RAM
 Avoid simultaneous memory
modifications
 Sending task accesses the
memory until pointer is queued

 Receiving task accesses the
memory after the pointer is
received from the queue
 NO ACCESS IN BETWEEN!
 Make sure RAM being pointed
is valid
 DO NOT USE STACK!
RAM
Tail
Head
2010
© 2012 Renesas Electronics America Inc. All rights reserved.25
Lab Exercise 2 – You can start the lab now