Usable Simulink Embedded Coder Target for Linux

Michal Sojka, Pavel Píša

Czech Technical University in PragueFaculty of Electrical Engineering

Department of Control Engineering

16th Real-Time Linux WorkshopOctober 12, 2014

Düsseldorf, Germany

M. Sojka, P. Píša Usable Simulink Embedded Coder Target for Linux RTLWS16 1 / 22

Motivation

I Not everybody is a programmerI Control engineers can design

control algorithms but cannotprogram them in C

I They use tools like Simulink to simulate their algorithmsI They still want to run their algorithms on real hardware, not

just simulationsI Solution: Matlab/Simulink + automatic code generationI Control applications = real-time applications

I while (1) { read input; calculate control; write output }

I The generated code needs to run on RTOS, e.g. GNU/Linux

M. Sojka, P. Píša Usable Simulink Embedded Coder Target for Linux RTLWS16 2 / 22

Motivation

I Not everybody is a programmerI Control engineers can design

control algorithms but cannotprogram them in C

I They use tools like Simulink to simulate their algorithmsI They still want to run their algorithms on real hardware, not

just simulations

I Solution: Matlab/Simulink + automatic code generationI Control applications = real-time applications

I while (1) { read input; calculate control; write output }

I The generated code needs to run on RTOS, e.g. GNU/Linux

M. Sojka, P. Píša Usable Simulink Embedded Coder Target for Linux RTLWS16 2 / 22

Motivation

I Not everybody is a programmerI Control engineers can design

control algorithms but cannotprogram them in C

I They use tools like Simulink to simulate their algorithmsI They still want to run their algorithms on real hardware, not

just simulationsI Solution: Matlab/Simulink + automatic code generation

I Control applications = real-time applicationsI while (1) { read input; calculate control; write output }

I The generated code needs to run on RTOS, e.g. GNU/Linux

M. Sojka, P. Píša Usable Simulink Embedded Coder Target for Linux RTLWS16 2 / 22

Motivation

I Not everybody is a programmerI Control engineers can design

control algorithms but cannotprogram them in C

I They use tools like Simulink to simulate their algorithmsI They still want to run their algorithms on real hardware, not

just simulationsI Solution: Matlab/Simulink + automatic code generationI Control applications = real-time applications

I while (1) { read input; calculate control; write output }

I The generated code needs to run on RTOS, e.g. GNU/Linux

M. Sojka, P. Píša Usable Simulink Embedded Coder Target for Linux RTLWS16 2 / 22

Motivation

I Not everybody is a programmerI Control engineers can design

control algorithms but cannotprogram them in C

I They use tools like Simulink to simulate their algorithmsI They still want to run their algorithms on real hardware, not

just simulationsI Solution: Matlab/Simulink + automatic code generationI Control applications = real-time applications

I while (1) { read input; calculate control; write output }

I The generated code needs to run on RTOS, e.g. GNU/Linux

M. Sojka, P. Píša Usable Simulink Embedded Coder Target for Linux RTLWS16 2 / 22

What is Simulink?

I Widely used tool for design and simulation of dynamic systemsI Commercial, non-free program – a part of MatlabI Developed by MathWorksI In its core is a solver of differential equationsI Algorithm is drawn as a data-flow graph (= Simulink model)I Simulink can simulate itI Simulink can generate C code of the model

M. Sojka, P. Píša Usable Simulink Embedded Coder Target for Linux RTLWS16 3 / 22

Why people use it?

M. Sojka, P. Píša Usable Simulink Embedded Coder Target for Linux RTLWS16 4 / 22

Code generation in Simulink

I Example:Sine Wave

Product

3

Constant

Pin 1

ErrFlag

Analog Input

Pin 1 ErrFlag

Analog Output

double in1, out1;in1 = adc_read(1);out1 = sin(t) + 3 * in1;dac_write(1, out1);

I Simulink Coder & Embedded CoderI Code generation target

I Template for “main.c”I Template for MakefileI I/O blocks

M. Sojka, P. Píša Usable Simulink Embedded Coder Target for Linux RTLWS16 5 / 22

Code generation in Simulink

I Example:Sine Wave

Product

3

Constant

Pin 1

ErrFlag

Analog Input

Pin 1 ErrFlag

Analog Output

double in1, out1;in1 = adc_read(1);out1 = sin(t) + 3 * in1;dac_write(1, out1);

I Simulink Coder & Embedded CoderI Code generation target

I Template for “main.c”I Template for MakefileI I/O blocks

M. Sojka, P. Píša Usable Simulink Embedded Coder Target for Linux RTLWS16 5 / 22

Can Simulink generate code that runs on Linux?

Yes, but. . .

M. Sojka, P. Píša Usable Simulink Embedded Coder Target for Linux RTLWS16 6 / 22

Can Simulink generate code that runs on Linux?

Yes, but. . .

M. Sojka, P. Píša Usable Simulink Embedded Coder Target for Linux RTLWS16 6 / 22

Problems of Simulink code generation targets for Linux

I Very good support for popular embedded boards(Raspberry Pi, BeagleBone, . . . )

I Can only be installed on Windows hosts /I Other Linux targets are fortunately supported via “IDE Link”

I Uses Eclipse IDE to compile and run the code /I Slow! /

I Generated code uses POSIX timersI POSIX timers do not guarantee real-time properties (latencies)

even under preempt_rt /

M. Sojka, P. Píša Usable Simulink Embedded Coder Target for Linux RTLWS16 7 / 22

Problems of Simulink code generation targets for Linux

I Very good support for popular embedded boards(Raspberry Pi, BeagleBone, . . . )

I Can only be installed on Windows hosts /

I Other Linux targets are fortunately supported via “IDE Link”I Uses Eclipse IDE to compile and run the code /I Slow! /

I Generated code uses POSIX timersI POSIX timers do not guarantee real-time properties (latencies)

even under preempt_rt /

M. Sojka, P. Píša Usable Simulink Embedded Coder Target for Linux RTLWS16 7 / 22

Problems of Simulink code generation targets for Linux

I Very good support for popular embedded boards(Raspberry Pi, BeagleBone, . . . )

I Can only be installed on Windows hosts /I Other Linux targets are fortunately supported via “IDE Link”

I Uses Eclipse IDE to compile and run the code /I Slow! /

I Generated code uses POSIX timersI POSIX timers do not guarantee real-time properties (latencies)

even under preempt_rt /

M. Sojka, P. Píša Usable Simulink Embedded Coder Target for Linux RTLWS16 7 / 22

Problems of Simulink code generation targets for Linux

I Very good support for popular embedded boards(Raspberry Pi, BeagleBone, . . . )

I Can only be installed on Windows hosts /I Other Linux targets are fortunately supported via “IDE Link”

I Uses Eclipse IDE to compile and run the code /I Slow! /

I Generated code uses POSIX timersI POSIX timers do not guarantee real-time properties (latencies)

even under preempt_rt /

M. Sojka, P. Píša Usable Simulink Embedded Coder Target for Linux RTLWS16 7 / 22

Problems of Simulink code generation targets for Linux

I Very good support for popular embedded boards(Raspberry Pi, BeagleBone, . . . )

I Can only be installed on Windows hosts /I Other Linux targets are fortunately supported via “IDE Link”

I Uses Eclipse IDE to compile and run the code /I Slow! /

I Generated code uses POSIX timersI POSIX timers do not guarantee real-time properties (latencies)

even under preempt_rt /

M. Sojka, P. Píša Usable Simulink Embedded Coder Target for Linux RTLWS16 7 / 22

POSIX timers under preempt_rt Linux

I POSIX timers use signals to notify user space about theirexpiration

I Signal delivery path uses sleeping locks under preempt_rtI Deferred to softirqI Softirqs are:

I executed in the context of arbitrary task or ksoftirqdI executed with random (e.g. non-real-time) priority

M. Sojka, P. Píša Usable Simulink Embedded Coder Target for Linux RTLWS16 8 / 22

Is there better code generationtarget?

Yes

ERT_LINUX

M. Sojka, P. Píša Usable Simulink Embedded Coder Target for Linux RTLWS16 9 / 22

ERT_LINUX code generation target

I Goal: Minimalist target which reuses as much Simulink codeas possible (not that easy)

I No Eclipse needed ,I Uses clock_nanosleep() for timing ,I External modeI Works both natively and with cross-compiling

http://lintarget.sf.net

M. Sojka, P. Píša Usable Simulink Embedded Coder Target for Linux RTLWS16 10 / 22

ERT_LINUX I/O support

I MF624: PCI data acquisition cardI Digital IO, Analog IO, PWM outI Counters (can be used for PWM input!)I Incremental encoder inputI Based on UIO driver ⇒ no syscall overhead

I CAN bus transmit/receiveI Some support for Raspberry PiI No Comedi yet

M. Sojka, P. Píša Usable Simulink Embedded Coder Target for Linux RTLWS16 11 / 22

ERT_LINUX I/O support

I MF624: PCI data acquisition cardI Digital IO, Analog IO, PWM outI Counters (can be used for PWM input!)I Incremental encoder inputI Based on UIO driver ⇒ no syscall overhead

I CAN bus transmit/receiveI Some support for Raspberry Pi

I No Comedi yet

M. Sojka, P. Píša Usable Simulink Embedded Coder Target for Linux RTLWS16 11 / 22

ERT_LINUX I/O support

I MF624: PCI data acquisition cardI Digital IO, Analog IO, PWM outI Counters (can be used for PWM input!)I Incremental encoder inputI Based on UIO driver ⇒ no syscall overhead

I CAN bus transmit/receiveI Some support for Raspberry PiI No Comedi yet

M. Sojka, P. Píša Usable Simulink Embedded Coder Target for Linux RTLWS16 11 / 22

Applications/demos

M. Sojka, P. Píša Usable Simulink Embedded Coder Target for Linux RTLWS16 12 / 22

PMSM motor simulationHardware-in-the-loop (HIL) simulation

Infineon TriBoard running a motor control algorithmPC

Motor & fault simulation

MF

624

I/O

car

d

PCLinux, CANCAN attacks

Linux, preempt_rt

PCInfoneon DeviceAccess Server (DAS)

CAN bus

Inte

rfac

e bo

ard

USB(serial line,JTAG, ...)

I Analysis of how does security influences safetyI PMSM motor simulation @ 20 kHzI Hand-written motor control algorithm runs on real hardwareI Message authentication on CANbus + brute force attacks

M. Sojka, P. Píša Usable Simulink Embedded Coder Target for Linux RTLWS16 13 / 22

Robot with parallel kinematic structure

I 4 DC motors, 4 incremental encoders, other I/OsI Presented at Embedded world 2014I Sampling period 1ms but complex computationsI More reliable that previously used Windows target

M. Sojka, P. Píša Usable Simulink Embedded Coder Target for Linux RTLWS16 14 / 22

Motor control on Raspberry Pi

I Final task for students of our real-time course:I Create software motor controller on an embedded PowerPC

board with VxWorks

I Can the same be implemented on Raspberry Pi with Linux?

M. Sojka, P. Píša Usable Simulink Embedded Coder Target for Linux RTLWS16 15 / 22

M. Sojka, P. Píša Usable Simulink Embedded Coder Target for Linux RTLWS16 16 / 22

Hardware

PWM

GPIOsRasp

berr

y P

i –

P1

CHB

CHA

IRC

HI DRV

LO DRV

IN

HI DRV

LO DRV

IN

DCMOTOR

Motor Power Supply

DIR

I As simple as possibleI Four NOR gates (SN74HCT02)I H-bridge (L6203)

M. Sojka, P. Píša Usable Simulink Embedded Coder Target for Linux RTLWS16 17 / 22

Incremental encoder (IRC) processing

I The most demanding partI IRC signal: 0 – 20 kHzI Every edge generates an interrupt (up to 80 k interrupts/sec)I Kernel driver to calculate the position

I Sustainable IRQ frequency up to ≈ 32 kHzI Further improvement: Use of ARM FIQ

M. Sojka, P. Píša Usable Simulink Embedded Coder Target for Linux RTLWS16 18 / 22

Incremental encoder (IRC) processing

I The most demanding partI IRC signal: 0 – 20 kHzI Every edge generates an interrupt (up to 80 k interrupts/sec)I Kernel driver to calculate the positionI Sustainable IRQ frequency up to ≈ 32 kHzI Further improvement: Use of ARM FIQ

M. Sojka, P. Píša Usable Simulink Embedded Coder Target for Linux RTLWS16 18 / 22

IRC processing details

GPIOs

Rasp

berr

y P

i

CHB

CHA

IRC

Hard IRQ

IRQ threadedhandler

I Position calculation works better if derived from the order ofIRQs than from the signal values read in the handler.

I FIFO run queue preserves order!

M. Sojka, P. Píša Usable Simulink Embedded Coder Target for Linux RTLWS16 19 / 22

Demo: Raspberry Pi motor controller

sfIRCInput

IRC0

int32 0

IRC-display

Convert

IRC int32 to Real

double

IRC-scope

-0.01

ManualPWM

double

sfPWMwDirOutput

PWMwDirManualPWM

Control

double Opt. PSD Controller

w RSTsrred I

u

I P

Subsys PSD

double

0

PositionRequest

double

0

RESET

double

ActiveOutputRange

double-K-

AntiWindup

double

Position

double

Convert

To int

uint8

0.05976

PWM-display

Pos

Trajectory

double

PWM

M. Sojka, P. Píša Usable Simulink Embedded Coder Target for Linux RTLWS16 20 / 22

Demo: Raspberry Pi & CAN

M. Sojka, P. Píša Usable Simulink Embedded Coder Target for Linux RTLWS16 21 / 22

Conclusion

I ERT_LINUX target worksI Used in several applicationsI Does not suffer from serious problems as original MathWorks

code generation targets.I Limited support for I/Os – Blocks for Comedi are on our todo

listI It might be possible to use our target with other I/O blocks

(e.g. from MathWorks)

Thank you!

M. Sojka, P. Píša Usable Simulink Embedded Coder Target for Linux RTLWS16 22 / 22

Conclusion

I ERT_LINUX target worksI Used in several applicationsI Does not suffer from serious problems as original MathWorks

code generation targets.I Limited support for I/Os – Blocks for Comedi are on our todo

listI It might be possible to use our target with other I/O blocks

(e.g. from MathWorks)

Thank you!M. Sojka, P. Píša Usable Simulink Embedded Coder Target for Linux RTLWS16 22 / 22