Giotto

A Time-Triggered Language for Embedded Programming

Thomas A. Henzinger, Benjamin Horowitz

Christoph M. Kirsch, Rupak Majumdar

UC Berkeley

Embedded Programming

• Giotto aims at hard real-time applications

• Giotto is time-triggered

• Giotto is platform independent

• Giotto consists of ports, tasks, modes

• Giotto works, with VxWorks, Ptolemy

Functionality & Timing

Control EngineerControl Design

Applicationdesignsvalidatessimulates

Software EngineerPlatform

Implementationdecomposesimplementstests

First Challenge

Compilation

Platform

Implementation

Second Challenge

Software Engineer

decomposesimplementstests

A Task

Abstract Syntax of a Task

f

Abstract Syntax of a Task

f

State

Abstract Syntax of a Task

fInput ports

State

Abstract Syntax of a Task

fInput ports

State

Output ports

Abstract Syntax of a Task

fInput ports

State

Output ports

Frequency

Semantics of a Task

fInput ports

State

Output ports

Frequency 10ms

Semantics of a Task

fInput ports

State

Output ports

Time

Task

Frequency 10ms

Semantics of a Task

fInput ports

State

Output ports

Time

Task

Frequency 10ms

Semantics of a Task

fInput ports

State

Output ports

Time

Task

Read @ time t

Frequency 10ms

Semantics of a Task

fInput ports

State

Output ports

Time

Task

Read @ time t

Frequency 10ms

Write @ time t+10ms

Semantics of a Task

fInput ports

State

Output ports

Time

Task

Read @ time t

Frequency 10ms

Write @ time t+10ms

Don’t care

A Connection

Input ports Output portsf

State

Abstract Syntax of a Connection

f

State

Constant

Abstract Syntax of a Connection

f

State

Input port Output port

Semantics of a Connection

f

State

f

State

Semantics of a Connection

f

State

f

State

Time

Task

Semantics of a Connection

f

State

f

State

Time

Task

Write @ time t

Semantics of a Connection

f

State

f

State

Time

Task

Write @ time t Read @ time t

Semantics of a Connection

f

State

f

State

Time

Task

Write @ time t Read @ time t

0 time

Two Tasks

PInput ports Output ports

Two Tasks

PInput ports Output ports

QInput ports Output ports

Connections

P

Q

Connections

P

Q

Connections

P

Q

Different Periodicity

P

Q

Different Periodicity

Time

Task

P

Q Q

Semantics

Time

Task

P

Q Q

Semantics

Time

Task

P

Q Q

t t+10ms

Semantics

Time

Task

P

Q Q

t t+10mst

Semantics

Time

Task

P

Q Q

t t+10mst t+5ms t+5ms

Semantics

Time

Task

P

Q Q

t t

Connections

P

Q

Semantics

Time

Task

P

Q Q

t t

Connections

P

Q

Semantics

Time

Task

P

Q Q

t t

Semantics

Time

Task

P

Q Q

t+5mst

Don’t care

Semantics

Time

Task

P

Q Q

t+5ms t+5ms

Semantics

Time

Task

P

Q Q

t+5ms t+5ms

Semantics

Time

Task

P

Q Q

t+5ms t+5ms

Semantics

Task

P

Q Q

t+10ms t+10ms

Semantics

Task

P

Q Q

t+10ms t+10ms

Semantics

Task

P

Q Q

t+10ms t+10ms

Theory !

A Giotto program is a single set of tasks,

so far

Is this enough?

Theory = Practice ?

• Yes, we have sufficient computation and communication resources!=> A single set of tasks is enough

Theory = Practice ?

• Yes, we have sufficient computation and communication resources!=> A single set of tasks is enough

Fin

Theory = Practice ?

• Yes, we have sufficient computation and communication resources!=> A single set of tasks is enough

Fin

• No, we have to share resources!=> with modes

Practice !

A mode is a set of tasks.

A Giotto program is a set of modes.

A Giotto program is a partitioning

of the set of all required tasks.

FAQ: Time vs. Events

Q: How about events?

A: Use modes!

A Mode

Abstract Syntax of a Mode

P

Q

Abstract Syntax of a Mode

P

Q

Abstract Syntax of a Mode

P

Q

Abstract Syntax of a Mode

P

Q

EntryPort

Abstract Syntax of a Mode

P

Q

EntryPort

Period

Semantics of a Mode

P

Q

EntryPort

Period10ms

1

2

Concrete Syntax

mode m ( ) period 10 ms

{

taskfreq 1 do int x = P ( ) ;

taskfreq 2 do int y = Q ( x, y ) ;

}

A Mode Switch

M M’

M M’

Predicate

Abstract Syntax of a Mode Switch

M M’

Predicate

Abstract Syntax of a Mode Switch

Frequency

M M’

Predicate

Abstract Syntax of a Mode Switch

Frequency

Connection

M M’

Predicate

Abstract Syntax of a Mode Switch

Frequency 5ms

Connection

Mode M

P

Q

Period10ms

1

2

Mode M

P

Q

Period10ms

1

2

Connection

Mode M’

Connection

Mode M’

P1

Connection

Mode M’

P

R

1

4

Connection

Mode M’

P

R

1

4

Connection

Mode M’

P

R

1

4

Connection

Mode M’

P

R

1

4

Connection

Mode M’

P

R

1

4

Connection

Period10ms

Concrete Syntaxstart m ( ) {

mode m ( ) period 10 ms entryfreq 1 {

taskfreq 1 do int x = P ( ) ;

taskfreq 2 do int y = Q ( x, y ) ;

exitfreq 2 if y = 5 then m’ ( y ) ;

}

mode m’ ( int z ) period 10 ms entryfreq 2 {

taskfreq 1 do int x = P ( ) ;

taskfreq 4 do int u = R ( x, z ) ;

}

}

Semantics of a Mode Switch

Task

P

Q Q

Time

Semantics of a Mode Switch

Task

P

Q Q

Mode Switch @ t+10ms t+10ms

Semantics of a Mode Switch

Task

P

Q Q

Mode Switch @ t+5ms t+5ms Time

Semantics of a Mode Switch

Task

P

Q

TimeMode Switch @ t+5ms

Mode M’

P

R

1

4

Semantics of a Mode Switch

Task

P

Q

t+5ms Time

R

t+5ms

Semantics of a Mode Switch

Task

P

Q

t+5ms Time

R R

t+5ms t+7.5ms

Semantics of a Mode Switch

Task

P

Q

t+5ms

R R

t+5ms t+7.5ms t+10ms

Semantics of a Mode Switch

Task

P

Q

t+5ms

R R

t+5ms Time

Mode M

P

Q

1

2

Connection

Semantics of a Mode Switch

Task

P

Q

t+5ms

R R

t+5ms Time

Semantics of a Mode Switch

Task

P

Q R R

Mode Switch finished @ t+5ms Time

Mode M’

P

R

1

4

Connection

Semantics of a Mode Switch

Task

P

Q

t+5ms

R R

t+5ms Time

Mode M’

P

R

1

4

Connection

Semantics of a Mode Switch

Task

P

Q

t+5ms

R R

t+5ms Time

Mode M’

P

R

1

4

Connection

Semantics of a Mode Switch

Task

P

Q

t+5ms

R R

t+5ms Time

Semantics of a Mode Switch

Task

P

Q R R

Timet+7.5ms

Semantics of a Mode Switch

Task

P

Q R R

Timet+7.5ms

Semantics of a Mode Switch

Task

P

Q R R

Timet+7.5ms

Semantics of a Mode Switch

Task

P

Q R R

Timet+7.5ms

Semantics of a Mode Switch

Task

P

Q R R

t+10ms t+10ms

Semantics of a Mode Switch

Task

P

Q R R

t+10ms t+10ms

Semantics of a Mode Switch

Task

P

Q R R

t+10ms t+10ms

Semantics of a Mode Switch

Task

P

Q R R

t+10ms t+10ms

Functionality & Timing

Control EngineerControl Design

Applicationdesignsvalidatessimulates

Software EngineerPlatform

Implementationdecomposesimplementstests

First Challenge

Compilation

Platform

Implementation

Second Challenge

Software Engineer

decomposesimplementstests

Annotated Giotto

Giotto Compiler

Giotto Program

Platform

Giotto-Architecture

Giotto Compiler

Hosts, Nets, Performance

Giotto Program

Giotto-A Program

Platform

Giotto-Scheduler

Giotto Compiler

Task to Host, Priority

Hosts, Nets, Performance

Giotto Program

Giotto-A Program

Giotto-AS Program

Platform

Giotto-Communication

Giotto Program

Giotto Compiler

Giotto-A Program

Platform

Giotto-AS Program

Giotto-ASC Program

Task to Host, Priority

Hosts, Nets, Performance

Connection to Net, TDMA

Platform Dependency

Task

P

Q Q

Time

Platform Dependency

Task

P

Q Q

Time

Computation

Giotto-AS

Task

P

Q Q

Time

Host A

Host A Host A

Giotto-AS

Task

P

Q Q

Time

Host A

Host A Host A

2.

1.1.

Platform Dependency

Task

P

Q R R

Time

Platform Dependency

Task

P

Q R R

Time

Communication

Platform Dependency

Task

P

Q R R

Time

Communication

Giotto-ASC

Task

P

Q R R

Time

Host A

Host B CC

Giotto-ASC

Task

P

Q R R

Time

Host A

Host B CC

Network CNetwork C

Giotto-ASC

Task

P

Q R R

Time

Host A

Host B CC

Network CNetwork C

t+10mst

Giotto-ASC

Task

P

Q R R

Time

Host A

Host B CC

Network CNetwork C

t+10mst

Giotto-ASC

Task

P

Q R R

Time

Host A

Host B CC

Network CNetwork C

t+10mst

Summary

Control Design

Application

Platform

Implementation

Functionality & Timing

Control Engineer

Software Engineer Compilation

Demo