1. Arthi Varadarajan and Dr. James M. Conrad
MicroC/OS-II, a Real-Time Kernel on the ATmega128L Microcontroller.
Lee College of Engineering Department of Electrical and Computer Engineering
Arthi Varadarajan and Dr. James M. Conrad
Introduction
The purpose of this project was to embed a real time kernel on the microcontroller ATmega128L and demonstrate the multitasking capability through an application running on the STK 500/501 board.
The MicroC/OS-II was chosen as the operating system because of its:
simplified design process,
preemptive RTOS time critical events which could be handled quickly and efficiently,
better usage of resources by providing valuable services like mailboxes,queues,semaphores.
MicroC/OS-II
MicroC/OS-II is a highly portable, ROMable, scalable, preemptive real-time, multitasking kernel (RTOS) for microprocessors and microcontrollers. Written in ANSI C for maximum portability, MicroC/OS-II has been ported to more than 40 different processor architectures ranging from 8- to 64-bit CPUs. Certifiable for use in safety-critical systems, this RTOS has been proven to be robust, reliable, and safe enough to use in your own applications.
UC/OS2 Hardware/Software Architecture
APPLICATION SOFTWARE
(Your Code!)
UC/OS-2
(Processor-Independent
Code)
UC/OS2 Configuration
(Application- Specific)
UC/OS2 Port
(Processor specific code)
CPU
Software
Timer
Hardware
AVR Studio® is an Integrated Development Environment for writing and debugging AVR applications in Windows® 98/XP/ME/2000 and Windows NT® environments. AVR Studio provides a project management tool, source file editor and chip simulator.
Research Highlights
A considerable amount of research was done in porting a real time operating system to the ATmega 128L. The source code for the MicroC/OSII was integrated with the port file configurations for the microcontroller. A board support package for the hardware configurations was also created. After the operating system was ported, a simple application was run on the target board which involved blinking one of the two LED’S alternately, thereby demonstrating the multitasking capability.
ATMEL ATmega128L is the microcontroller used for the board. This low power, high performance AVR® 8-bit microcontroller has an operating voltage range of 2.7V to 5V. It also has 128K in-system programmable flash, 4K internal RAM, and JTAG interface for programming.
TEST SET UP
The above figure is a hardware layout of the test set up. The STK 501 board with the ATmega128L chip sits on top of the STK500 board. The LEDS are connected to the respective ports through the connectors. The boards are powered through the JTAG mk11.
CONCLUSION
Through this project, we understand that porting a real time kernel to any microcontroller can be adapted in a similar fashion. With a thorough understanding of operating system concepts, the principle can be applied across any microcontroller and potentially tap their inherent capability.
Contact info: Dr James M. Arthi University of North Carolina at Charlotte, Electrical and Computer Engineering Department, 9201 University City Blvd, Charlotte, NC 28223