Freertos and LPC Microcontrollers: Richard Barry Design West, San Jose, 2013

FreeRTOS and LPC Microcontrollers
Richard Barry
Design West, San Jose, 2013
Introductions
Real Time Engineers Ltd.

– FreeRTOS™
– FreeRTOS+™
WITTENSTEIN high integrity systems

– OpenRTOS®
– SafeRTOS®
Richard Barry
Director, Real Time Engineers Ltd
Founder, the FreeRTOS project
Copyright 2013 Real Time Engineers Ltd.

Agenda
Why would I want an RTOS?

What is FreeRTOS? What is FreeRTOS+?
The FreeRTOS value proposition
Using FreeRTOS
FreeRTOS running on LPC
LPCOpen, a complete embedded solution from NXP
Copyright 2013 Real Time Engineers Ltd. 3

April 25, 2013
Why Would I Want an RTOS?
HOW CAN AN RTOS HELP ME?

Super Loop Designs

Super Loop Designs
Will it scale?

Scaling and Maintenance
Integration of COTS components
Code re-use
Mixed processing requirements
Concurrent team development
Testability
Mix of hard and soft real time
Scalable (not susceptible to application change)
Tolerant of hardware change

Code re-use

Interdependency between timing and functionality
Testability

The RTOS Alternative
Task #1 Task #2 Task #3
Delay (wait) until it is

Wait for a message
time to start the next Wait for interrupt
from another task
control cycle
Perform control
Process data Process message
function
Send a message to
Output results
another task
Task #4
Background
processing

The RTOS Alternative
Task #1 Task #2 Task #3
Delay (wait) until it is

Wait for a message
time to start the next Wait for interrupt
from another task
control cycle
Perform control
Process data Process message
function
Autonomous sequential tasks,
RTOS takes care of signaling, communication and timing
Send a message to
Output results
another task
Task #4
Background
processing

Code re-use
Testability
Copyright 2013 Real Time Engineers Ltd.11

Code re-use

Decoupled, functionally cohesive code
Testability

Agenda

Using FreeRTOS

April 25, 2013
WHAT IS FREERTOS?

RTOS, Kernel or Scheduler?
RTOS
Executive
Scheduler

The RT In RTOS
Deterministic
– Hard real time – “it absolutely must”
– Soft real time – “it should”
T2 preempts T3 T1 preempts T2
Task1 (high, event)

Task2 (med, periodic)
Task3 (low, event)
Idle task
t1 t2 t3 t4 t5 t6 t7 t8 t9 t11 t13
t10 t12

For Microcontrollers
33 architectures and 18 tool chains
Real Time Linux

μCLinux, eCOS
Applicability
FreeRTOS
No Scheduler
Processor power

Moderated Open Source Real Time Kernel
is everywhere ....
Professionally developed, quality controlled, robust and supported

Downloaded more than 103,000 times in 2012
Polled top in class for the questions “which kernel are you currently
using?” and “which kernel are you most likely to use in your next project”
in the 2011, 2012 and 2013 EETimes Embedded Market Surveys

FreeRTOS Value Proposition
FreeRTOS offers lower project risks and a lower total cost of ownership
than commercial alternatives because:
It is fully supported and documented
Most people take products to market without ever contacting us, but
with the complete peace of mind that they could opt to switch to a fully
indemnified commercial license (with dedicated supports) at any time.

Is It Free, Even For Commercial Use?
Yes
– Moderated open source
– Proprietary code remains proprietary
Application Driver Middleware

Source Source Source
Closed Source
FreeRTOS API
Open Source
FreeRTOS Source

Under Constant Development
Latest features include

– Tick suppression for low power applications
– Queue sets
– Port optimised task selection
Without Tick Suppression
Interrupt
Scheduler
Task
Idle Task

Under Constant Development
Latest features include

– Tick suppression for low power applications
– Queue sets
– Port optimised task selection
With Tick Suppression
Interrupt
Scheduler
Task
Idle Task

FreeRTOS+ Ecosystem
FreeRTOS+
TCP/IP UDP/IP
Pre-built libraries for easy integration
Thread aware, Berkeley sockets
of TCP/IP and related protocols into
based, efficient UDP/IP stack
cost-sensitive applications
IO CLI
Add an open(), read(), write(), ioctl()
Enable your application to efficiently
peripheral interface to your
process command line input
application
Safety & Certification Trace
A pre-certified kernel for Get 15 graphically interlinked views of
microcontrollers, with a similar usage the trace, providing an unprecedented
model to FreeRTOS level of insight
Nabto SSL and TLS

Exciting new technology that re- State of the art networking security
defines the web device for embedded systems
RTOS Training
Expert instructor led RTOS training to
maximise productivity – delivered
Your Product Here?
online or on site

FreeRTOS+Trace

October 2012
Agenda

Using FreeRTOS

www.FreeRTOS.org

Source Files

FAQ

Task Example #1
/* Tasks always have the same prototype. */
void vProcessMessages( void *pvParameters )
{
for( ;; )
{
xQueueReceive( xQueue, &xMessage, portMAX_DELAY );
ProcessMessage( &xMessage );
}
/* A task cannot exit without first deleting itself. */

vTaskDelete( NULL );
}

Task Example #2
/* Tasks always have the same prototype. */
void vProcessMessages( void *pvParameters )
{
portTickType xLastWakeTime;
const portTickType xFrequency = 10;
/* Initialise the xLastWakeTime variable with the

current time. */
xLastWakeTime = xTaskGetTickCount();
for( ;; )
{
/* Wait for the next cycle. */
vTaskDelayUntil( &xLastWakeTime, xFrequency );
vPeriodicProcessingDoneHere();
}
}

Create a Task – Start the Scheduler
xTaskCreate( /* A pointer to the task function. */
aTask,
/* Textual name. */
"LED",
/* Dimensions of the task stack. */
configMINIMAL_STACK_DEPTH,
/* Parameters passed into the task. */
(void *) 0,
/* The priority of the task. */
2,
/* A handle for the task. */
NULL
);
vTaskStartScheduler();

Agenda

Using FreeRTOS

Featured Demo #1

Featured Demo #2

April 25, 2013
LPCOpen from NXP
LPCOpen is free software from NXP for use with NXP MCUs
– Peripheral drivers
– LPCUSBlib, with support for many classes
– SWIM (NXP‘s lightweight graphics library)
– Examples
Includes pre-ported third party open source and licensed software
– Support and examples for FreeRTOS
– LwIP network stack
– emWin (binary graphics library licensed from Segger for NXP customers)
– ChaN FatFs
– Cortex-M CMSIS DSP library
LPCOpen is available for download on www.lpcware.com

Benefits of LPCOpen
Supports all NXP Cortex-M based MCUs

Similar APIs across processor families
Available for Keil’s µVision, IAR’s EWARM, LPCXpresso
Supports hardware from Embedded Artists, NGX, Keil, Hitex, and more
Thoroughly tested, maintained, and documented code
Meaningful application examples using multiple peripherals, running
stand-alone or under an RTOS
Steadily increasing number of example applications, including USB
audio, HID, Web Server, etc

The LPCOpen platform structure
Core Library
Board layer
Chip layer emWin FreeRTOS
LwIP LPCUSBlib
IP layer SWIM
LPCOpen Platform
LPCUSBlib LwIP Peripheral emWin OS
examples examples examples examples examples
HID, CDC Webserver Power Save Touchscreen Dual Core OS

Mass Storage TCP/IP echo Dual Core Animation Tickless OS
Audio Internet radio CAN : :
Host : SCT : :
: : SGPIO
: :

Importing LPCOpen Stacks and Drivers

There is a lot more!
TAKING IT FURTHER

Thanks For Attending!

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FreeRTOS and LPC Microcontrollers

Real Time Engineers Ltd.

WITTENSTEIN high integrity systems

Copyright 2013 Real Time Engineers Ltd.

Why would I want an RTOS?

Copyright 2013 Real Time Engineers Ltd. 3

HOW CAN AN RTOS HELP ME?

Copyright 2013 Real Time Engineers Ltd. 4

Copyright 2013 Real Time Engineers Ltd. 5

Copyright 2013 Real Time Engineers Ltd. 6

Integration of COTS components

Mixed processing requirements

Concurrent team development

Mix of hard and soft real time

Scalable (not susceptible to application change)

Tolerant of hardware change

Copyright 2013 Real Time Engineers Ltd. 7

Integration of COTS components

Mixed processing requirements

Concurrent team development

Mix of hard and soft real time

Scalable (not susceptible to application change)

Tolerant of hardware change

Copyright 2013 Real Time Engineers Ltd. 8

Delay (wait) until it is

Copyright 2013 Real Time Engineers Ltd. 9

Delay (wait) until it is

Copyright 2013 Real Time Engineers Ltd. 10

Integration of COTS components

Mixed processing requirements

Concurrent team development

Mix of hard and soft real time

Scalable (not susceptible to application change)

Tolerant of hardware change

Copyright 2013 Real Time Engineers Ltd.11

Integration of COTS components

Mixed processing requirements

Concurrent team development

Mix of hard and soft real time

Scalable (not susceptible to application change)

Tolerant of hardware change

Copyright 2013 Real Time Engineers Ltd. 12

Why would I want an RTOS?

Copyright 2013 Real Time Engineers Ltd. 13

Copyright 2013 Real Time Engineers Ltd. 14

Copyright 2013 Real Time Engineers Ltd. 15

Task1 (high, event)

Copyright 2013 Real Time Engineers Ltd. 16

33 architectures and 18 tool chains

Real Time Linux

Copyright 2013 Real Time Engineers Ltd. 17

Professionally developed, quality controlled, robust and supported

Copyright 2013 Real Time Engineers Ltd.18

Copyright 2013 Real Time Engineers Ltd.19

Application Driver Middleware

Copyright 2013 Real Time Engineers Ltd. 20

Latest features include

Without Tick Suppression

Copyright 2013 Real Time Engineers Ltd. 21