Implementing RTOS on 8051: Issues and INCODE case study

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Implementing RTOS on 8051 Issues and INCODE
case study

• Lokesh Kumar
• (2001118)
• Under the guidance of
• Prof. M. Balakrishnan
• Bachelors Project Final Presentation
• Department of Computer Science Engineering
• IIT Delhi
• 12th May, 2005

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Presentation Outline

• Motivation
• 8051 Architecture
• Porting Rtker to 8051
• RTX-51 A commercial RTOS
• INCODE
• Challenges and Contribution

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Motivation

• Embedded Devices like Microcontrollers ubiquitous
  in
• Sensor Networks
• Image Processing
• Computer Vision etc.
• Nature of application demands
• Real Time Processing
• High Throughput.
• Microcontrollers with an RTOS offer an efficient
  platform for development of such applications.

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Motivation

• 8051 as an option for Microcontroller
• Low Cost
• Very Widely Used
• Rtker as the option for RTOS
• In-house Developed System
• Unique features like -
• Pluggable Scheduler
• Two way Interrupt Handling
• Logical separation of Hardware dependent and
  Independent code

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Presentation Outline

• Motivation
• 8051 Architecture
• Porting Rtker to 8051
• RTX-51 A commercial RTOS
• INCODE
• Challenges and Contribution

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8051 Architecture

• The Most Widely Used Microcontroller in the
  world.
• Developed by All Leading Manufacturers of
  Embedded Systems.
• 8-bit Harvard Architecture
• Central Processing Unit
• 4k Bytes ROM (80C51)
• 128 Bytes RAM
• Three 16-bit Counters/Timers
• Memory Addressing Capability
• 64k ROM and 64k RAM

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8051 Features

• Register Banks
• Efficient Execution of Context Switch
• Interrupt functions
• Hardware Interrupts
• Timer Flags
• Serial Port

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8051 Programming Model
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Presentation Outline

• Motivation
• 8051 Architecture
• Porting Rtker to 8051
• RTX-51 A commercial RTOS
• INCODE
• Challenges and Contribution

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Rtker

• Source Code of Rtker is
• C and Assemble Lang., GCC compiled
• Logical Separation of Hardware dependent and
  Independent code
• Porting Rtker to an architecture requires
• Writing Hardware dependent code of Rtker
• Compiling Hardware Independent dependent by GCC
• 8051 has no GCC support
• Keil C compiler in DHD Lab
• Porting Rtker will require
• Writing Hardware Dependent Independent code

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Issues

• Hardware Dependent Code includes
• Context Switch
• Interrupt Service Routines
• Trap Handlers
• Started with Porting Context Switch using
  Register Bank Feature
• Issues faced were
• Extreme Memory Constraints of 8051
• Upper Limit on Maximum Number of Threads to 4
• Two Kernel Threads (main bhalf)
• Two User Level Threads

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Presentation Outline

• Motivation
• 8051 Architecture
• Porting Rtker to 8051
• RTX-51 A Commercial RTOS
• INCODE
• Challenges and Contribution

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RTX-51

• Keil RTOS, available in DHD Lab
• Features
• Multi-tasking (Max. 16 tasks)
• Round Robin Scheduler
• Single chip Memory Requirement
• Comparison with Rtker
• Scheduler not pluggable
• Not portable (Source code in Assembly)

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RTX-51

• Tested with different Demo Applications
• Conclusions
• Stable, Flexible
• Round Robin can be disabled to achieve
  pre-emptive scheduling behaviour.

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Presentation Outline

• Motivation
• 8051 Architecture
• Porting Rtker to 8051
• RTX-51 A Commercial RTOS
• INCODE
• Challenges and Contribution

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INCODE

• Hardware Software Co-design Tool to implement
  small designs
• FPGA and Microcontroller based tool
• Low Cost

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Objective

• To run existing INCODE program as an
  application on RTX-51 on the microcontrollers of
  FPGA boards in DHD Lab for configuring FPGAs.

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Features of INCODE on RTX-51
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INCODE FPGA BOARD
FPGA
PLA
Micro Controller
XRAM
XROM
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Multi-Tasking

• A Task listens to Serial Port for incoming
  commands
• Another Independent Task Configures FPGA from ROM
• Simultaneous Execution of both tasks
• Tested
• Stable
• Reliable

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Presentation Outline

• Motivation
• 8051 Architecture
• Porting Rtker to 8051
• RTX-51 A Commercial RTOS
• INCODE
• Challenges and Contribution

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Challenges

• Providing Breakpoints in the Run Program
  Feature of INCODE
• Increasing the file download rate from PC to
  Microcontroller
• Redundant data may not be downloaded
• A new GUI can support the new file transfer
  protocol

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Contribution

• Study of issues in porting Rtker on 8051
• A Real Time responsive Multi-Task Enabled INCODE
  Program
• New features added in INCODE
• Downloading Configuration Files from XROM.

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• Thank You !