Development of a Front end for an Aerospace

Embedded system having a serial interface

PROJECT DONE AT : DRDO

PROJECT TEAM MEMBERS :

K.SRI LAASYA

P.MANOJ KUMAR

Background score

• The latest technologies being developed now-a-days primarily aim towards

• automation in real-time. Some of the illustrative examples are NASA’s Mars rovers,

• Robots, Mobile Cellular phones, DVD players, etc. Each of these applications performs

• a specific defined function. Such systems, which pave way for automation, are based on

• the basic concept called “REAL-TIME EMBEDDED SYSTEM”.

INTRODUCTION

REAL-TIME SYSTEMS : -• Timeliness is the single most important aspect of a real-time

system. These systems respond to a series of external inputs, which arrive in an unpredictable fashion.

• The real-time systems process these inputs, take appropriate decisions and also generate output necessary to control the peripherals connected to them.

• “A real-time system is one in which the correctness of the computations not only depends upon the logical correctness of the computation but also upon the time in which the result is produced.

UNDERSTANDING THE REALTIME EMBEDDED SYSTEM

• The design of a real-time system must specify the timing requirements of the system and ensure that the system performance is both correct and timely.

There are three types of time constraints:• HARD: A late response is incorrect and implies a system

failure. An example of such a system is of medical equipment monitoring vital functions of a human body , where a late response would be considered as a failure.

• SOFT: Timeliness requirements are defined by using an average response time. If a single computation is late, it is not usually significant, although repeated late computation can result in system failures.

• An example of such a system includes airlines reservation systems.

• FIRM: This is a combination of both hard and soft timeliness requirements. The computation has a shorter soft requirement and a longer hard requirement.

• For example, a patient ventilator must mechanically ventilate the patient a certain amount in a given time period. A few seconds’ delay in the initiation of breath is allowed, but not more than that.

EMBEDDED SYSTEM

An embedded system is a combination of computer hardware, software and electro-mechanical parts tailored for a dedicated single or combinations of functions.

Ex: A computerized washing machine is an example of an embedded system . Embedded systems are usually constructed with the least powerful computers that can meet the functional and performance requirements.

This is essential to lower the manufacturing cost of the equipment .

AIM OF THE PROJECT

• The peripherals play a vital role in the functional performance of the OBC.

• The peripheral ICs have to be tested for accurate working before they are used in real-time.

• The testing procedure is thus carried out in real-time constraints by a real-time embedded program which is already existing in OBC.

• The testing procedures of various peripherals put together in that program and are called “Self Test” of the OBC.

• This project presents with the necessary knowledge about the various peripherals and the steps involved in the development of the front-end GUI for the OBC in VC++.

METHODOLOGY

• The testing procedure is carried out in real-time constraints by developing real time embedded programs.

• The testing procedures of various peripherals put together in the OBC embedded program and called “Self-Test” of the OBC.

• The “Self-Test” program is so called as the ICs are tested using the resources available on the OBC itself.

• The front-end GUI program on host PC is provided with the initialization and opening of the RS-232 serial communication port.

• Then the device, for which the health to be monitored is transmitted as a serial number from the device list to OBC embedded program.

• So, the GUI program on host PC will be waiting for a character from OBC to know the status of the selected device.

• The GUI program can be used for number of devices in the list and same device for number of times.

• Once all the devices are checked then the serial port communication can be disconnected and the application can be closed.

SIGNIFICANCE OF WORK

• The peripheral ICs play a vital role in the functional performance of the OBC.

• The peripherals ICs thus have to be tested for accurate working before they are used in-flight.

• The testing procedure is carried out in real-time constraints by using the real time embedded programs developed in the present Self-Test program.

• The results obtained after testing are helpful in replacing the peripherals with redundancy.

• On Board Computer is the central processing unit used on any aerospace vehicle.

• Hence, its applicability mainly includes areas where remote controlling with less human interference is required.

• Such application areas are satellites, missiles etc.

All these application areas are mission critical where failure of OBC’s functionality may lead to catastrophic results.

• The present work, OBC’s Self-Test, monitors the functional performance of OBC’s peripherals and prevents undesired effects resulting from its failure.

SOFTWARE REQUIREMENT SPECIFICATIONS

Software specifications :• Operating System: Window XP• Development platform: MS Visual C++ (Ver. 6.0).

Hardware specifications : • Processor: Intel Pentium 4• Clock : 2.4GHz• RAM : 512 MB• Hard Disk: 20GB• Keyboard: Standard 101/102 key• Mouse: PS/2 Optical• Serial Port: COM1 to COM4

PERIPHERAL OVERVIEW

• On Board Computer is a Real-Time Embedded System. It is the central information processing system in the airborne vehicle.

• It implements navigation, guidance and control operations of an aerospace vehicle.

• It receives information from ground control centers, sensors, processes real-time data with computational accuracy and sends desired control commands to Actuation System

• Navigation : where to go • Guidance : when to go • Control : how to go

Setup process in typical cross-platform development

ONBOARD COMPUTER (OBC):

• On Board Computer is a Real-Time Embedded System.• It is the central information processing system in the airborne

vehicle. It implements navigation, guidance and control operations of an aerospace vehicle.

• It receives information from ground control centers, sensors, processes real-time data with computational accuracy and sends desired control commands to Actuation System.

• OBC is a Ruggedized system which can withstand harsh environments, Climatic tests (-20°C and +50°C), Vibration, Shock, Bump tests in extreme conditions.

ONBOARD COMPUTER -OVERVIEW

• On Board Computer (OBC)consists of 80486DX dual processor i.e. it uses two 80486DX processors for meeting the high speed processing requirements of large number of parameters.

• OBC communicates with the external world i.e. a PC in the Self-Test procedure, through an 8274, Multi-Protocol Serial Controller.

• 8274 does the task of high-speed serial data communication in asynchronous mode .

• 82C54’s counter 0 is used for the Real-Time clock generation, which is used for periodic monitoring of various system parameters.

• 8255A is a Programmable Peripheral Interface, which is having 24 I/O pins are used for switch closing operations of the relays connected.

• 82C59, which is a Programmable Interrupt Controller, is used for generating priority interrupts for the processor.

NEED FOR TESTING OF PERIPHERALS

• Testing of peripherals is of paramount importance in mission critical hard real time embedded systems such as the on board computer which drive sensitive units like an aerospace vehicle or an automobile.

• Computer malfunction is considered one of the major cause for most accidents involving aero planes , ballistic missiles or space rockets.

TOP DOWN STRUCTURE OF FUNCTIONS AND DATA FLOW

DATAFLOW DIAGRAM FOR THE APPLICATION PROGRAM OF FRONT END GUI

WELCOME SCREEN

OBC SELFTEST DIALOG BOX

PORT CONFIGURATION PARAMETERS

SELECTION OF COMMUNICATION PORT

SELECTION OF BAUD RATE

SELECTION OF STOP BITS

SELECTION OF DATA BITS

SELECTION OF FLOW CONTROL

DISPLAY OF PORT SETTINGS SELECTED

INTIALIZING THE COMMUNICATION PORT

SENDING THE SELECTED DEVICE OPTION FOR HEALTH CHECK

RESPONSE FROM OBC FOR MPSC HEALTH CHECK

RESPONSE FROM OBC FOR PPI HEALTH CHECK

RESPONSE FROM OBC FOR RTC & PIC HEALTH CHECK

RESPONSE FROM OBC FOR ADC & DAC HEALTH CHECK

TO DISCONNECT THE COMMUNICATION PORT AND TO UNINTIALIZE

Conclusion

• On Board Computer plays a major role in the data acquisition and processing functions of any aerospace vehicle.

• The Self-Test procedure developed is significant and helpful to avoid the failure of any airborne mission critical systems.

• The GUI is very much useful in health monitoring of the individual peripheral ICs via serial communication from the host PC.

• The application sends the request and waits till the response from the OBC is received.

• On Reception of the response a message will be displayed either the device health is “OK” Or “NOTOK” in the “Result/Device Status” edit box.

THANK YOU