BURTOS

1
BURTOS

• Masters Research Defense
• Dexter Travis

2
Agenda

• Introduction
• Constraints
• Research
• Objectives
• Design
• Features
• Performance
• Enhancements
• Questions

3
Introduction

• A real-time operating system (RTOS)Generally
  pronounced as Are-toss is a multitasking
  operating system intended for real-time
  applicationsan RTOS provides facilities which,
  if used properly, guarantee deadlines can be met
  generally (soft real-time) or deterministically
  (hard real-time)An RTOS is valued more for how
  quickly and/or predictably it can respond to a
  particular event than for the given amount of
  work it can perform over time. Key factors in an
  RTOS are therefore a minimal interrupt latency
  and a minimal thread switching latency. 1

4
Constraints

• Platform
• Silicon Laboratories 8051 C8051F040
• Tool Set -Compiler (NA)
• Originally constrained to SDCC relaxed to include
  Keil
• Time Line
• Completion Spring Semester 2008
• Part Time Student, with full-time career, wife
  and baby on the way.
• Educational Goal
• End product reusable and understandable by BSEE
  entering Senior year.

5
8051 and the Stack Pointer

• 8051 Harvard Context Switch

• Von Neuman Context Switch

Memory
XDATA
DATA
CODE
SP
SP
HW STACK
STACK 2
HW STACK
STACK 1
HW STACK
STACK 1
SP
STACK 2
STACK 3
STACK 1
HW STACK
STACK 1
STACK 4
STACK 2
STACK 3
CODE
STACK 4
6
Research
2

• 2006 Embedded Systems Design Magazine Poll
• Used uC/OS and RTX as baselines for 8051 capable
  OS
• uC/OS full featured pre-emptive, semaphore, mutex
  etc
• Keil RTX minimally features cooperative

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Objectives

• Real Time Kernel with commercially reasonable
  feature set
• Pre-emptive multi-tasking
• Semaphores
• Interrupt abstraction
• Signals/Message Passing
• Minimal Dynamic Memory Allocation
• Learning Tool for future projects
• Transfer of knowledge gains

8
Design (Kernel Overview)
9
Design (Context Switch) - Initial
10
Design (Context Switch) - Final
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Features Actually Implemented

• Pre-emptive multi-tasking (without priority)
• Semaphores
• Signals
• Interrupt Callbacks, enable and disable
  abstraction
• Wait/Sleep
• Yield
• Signal/Semaphore Timeouts
• Error Reporting Mechanism (ERRNO)
• Zero Dynamic Memory Allocation
• Configurable Tick Period
• Configuration Constants
• Conditional Compile for easier HW timer selection
  and SDCC switch over

12
Results The Core
13
Results The Core
14
Results The Core
15
Results The Core
16
Results The Core
17
Results
18
Results
19
Enhancements

• Port to SDCC
• CAN/RS232 Application Tasks Built on the Kernel
• Enhance Monitoring Task

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Questions
21
References

• 1 Real-Time Operating System Wikipedia
  http//en.wikipedia.org/wiki/Real-time_operating_s
  ystem retrieved on May 4, 2008.
• 2 Operating Systems on the Rise Embedded
  Systems Design Magazine by Jim Turley
  http//www.embedded.com/columns/surveys/187203732?
  _requestid61891 retrieved on 12/29/2007