Remote laboratory design for teaching students in the use of microcontrollers.

Luculescu, Marius Cristian ; Lache, Simona

1. INTRODUCTION

Exponential development of the Internet in recent years has brought major changes not only in computers domain but also in the people's life. The Internet is making the transition from an offline way of life, with time and space limitations, to an online one, in which the constraints of time and space are simply removed (ILhyeon et al., 2008).

This paradigm has affected the education domain also, causing the emergence of new methods of learning, materialized in the so-called virtual laboratories and laboratories that provide remote access (remote laboratories). It is very important to make a clear distinction between the two concepts. Although both take into account the learning by experimentation or practice concept ("learning by doing"), within virtual laboratory the experiment is simulated by software using software packages most recognized in the field, such as LabVIEW, MATLAB, ORCAD and so on (Auer, 2001). Unlike the virtual labs, remote labs are designed so that to provide access to real experiments, conducted in real time, which can be tracked and controlled through the Internet.

2. PROBLEM FORMULATION

2.1 Problem Statement

Due to extremely high interest shown by students on learning how to work with microcontrollers in mechatronics we have decided to design and perform a series of tools with which students can access anytime, from anywhere, a large number of microcontroller development systems. All these tools must be designed to ensure the functions and benefits that a student would have when working with the physical system and have to be included in a so-called remote laboratory.

2.2 The Actual Stage in the Domain

Most of the tools used for training students through the Internet are virtual experiments, in which progress on the accumulation of new knowledge depends on the authenticity, key constraints and capabilities of software simulation, often limiting the creativity of the individual.

All these restrictions are removed in laboratories with remote access. The most important advantages offered by remote labs are (Auer, 2001):

* Providing access to students' experiments from anywhere, 24/7;

* Optimal and efficient use of expensive high-complexity equipment, better justifying such investments;

* Performing the real experiments, not simulated by software;

* Eliminating the risk of equipment damage by direct contact, after handling errors;

* Eliminating the risk of injury;

* No need to use laboratory personnel;

* Developing distance learning, allowing students to combine educational activities with work carried out within a company;

* Using an appropriate system of access management based on schedules, so that in busy periods each student may benefit of a time interval necessary to achieve the experiments.

Nowadays there are many worldwide laboratories with remote access. Reasons for designing our own laboratory take into account the low-cost, the possibility of having access to configure own applications, of using certain types of microcontroller development systems, of writing software for various hardware configurations and so on.

3. PROBLEM SOLUTION

3.1 System Description

The structure of the remote laboratory consists in two subsystems: a hardware one and a software one. The hardware subsystem contains a microcontroller development system named IMC500, with a serial interface for communication, an IP WEB camera and a Serial-to-Ethernet module (WIZ110SR). Both the camera and the module are connected to a switch for Internet access. The software subsystem is a client-server program. The client part is used on the student's PC for authentication, work session reservation and remote working with the microcontroller system. The server part is running on a server machine managing the remote connections, scheduling process, authentication process, starting and ending the working sessions and transferring the video and audio flow from the IP camera to the user (Fig. 1).

3.2 The Hardware Subsystem

In the initial stage, the remote lab has to provide access to seven IMC500 microcontroller development systems, based on 80C552 ROMless single-chip 8-bit microcontroller. This is a derivative of the 80C51 microcontroller family, having the same instruction set as the 80C51. The microcontroller has an 8-bit data bus and a 16-bit address bus for addressing 64KB of external memory. The first 32KB are implemented with an EPROM circuit and contains the monitor routines used for PC communicating, loading, running and debugging programs.

[FIGURE 1 OMITTED]

The last 32KB implemented on an SRAM circuit are for the user programs. The 80C552 microcontroller contains 256 bytes of internal read/write data memory, five 8-bit I/O ports, one 8-bit input port, two 16-bit timer/event counters (identical to the timers of the 80C51), an additional 16-bit timer coupled to capture and compare latches, a 15-source, two-priority-level, nested interrupt structure, an 8-input ADC with 10-bit resolution, a dual digital-to-analog converter (DAC) pulse width modulated interface, two serial interfaces (UART and I2C-bus), a "watchdog" timer and on-chip oscillator and timing circuits (***, 2008).

The IMC500 microcontroller development system contains:

* RS-232 compatible serial interface, full duplex;

* [I.sup.2]C serial bus;

* Two 8-bit external output ports;

* One 8-bit external parallel input port;

* One LCD port.

The IMC500 system is connected to a WIZ110SR Serial-to-Ethernet module using a DB9 connector. The other end of the interface is connected to a Fast-Ethernet switch through a RJ45 connector. WIZ110SR is a gateway module that converts RS-232 protocol into TCP/IP protocol. It enables remote gauging, managing and control of a device through the network based on Ethernet and TCP/IP by connecting to the existing equipment with RS-232 serial interface (***, 2009). The module contains an 8051 compatible microcontroller (MCU). When data is received from the serial port, it is sent to a specialized W5100 circuit by MCU. If any data is transmitted from Ethernet, it is received in the internal buffer of W5100 and sent to the serial port by MCU.

At the IMC500 system can be connected various types of input/output hardware modules, namely mono or bicolour LED modules, LCD, stepper motors, servo motors, temperature sensors, relays and so on and these are all done in different laboratory sessions.

The results of running a program on these modules, can be observed using an IP WEB camera.

3.3 The Software Subsystem

Each student that wants to use the remote laboratory will receive a username. With that username, he can connect to the server using a graphical user interface (GUI).

In the login process, if the username exists in the server database, the client will receive the right to choose a laboratory session on a certain IMC500 system. A schedule is displayed so that the user to choose a free time interval.

[FIGURE 2 OMITTED]

Then server will generate a password and send it to the student. The database contains the following information: username, password, session reserved starting date and time, session reserved ending date and time, connected time, disconnected time and so on.

Using the authentication data, student can connect to the remote laboratory. After the server validation, the session is opened and the client can use the GUI from Fig. 2 for working with the microcontroller development system. The WEB camera can be also activated or deactivated. With five minutes before the session will expire, an alert signal is generated if the next session is reserved for other user. If not, the current user is asked if he wants to continue with one more session. When the time is expired, the client is automatically disconnected by the management system.

4. CONCLUSIONS AND FUTURE WORK

The developed remote lab is a very useful tool for students and not only. They can write, load, test and debug programs anytime and from anywhere, just using a PC and an Internet connection. A special tutorial section for teaching microcontrollers can be accessed. Various types of application can be made (Luculescu, 2008).

As future work, students will be involved in and they asked for improving laboratory. New types of microcontroller development systems will be connected to this remote lab. A discussion forum will be integrated in the system.

5. REFERENCES

Auer, M. (2001). Virtual Lab versus Remote Lab, Proceedings of 20th ICDE World Conf. on Open Learning And Distance Education, 01-05 APRIL 2001, Dusseldorf, Germany

ILhyeon, M.; Saeron, H.; Kwansun, C., Dongsik, K.; Changwan, J.; Sunheum, L. & Sangyeon, W. (2008). A Remote Laboratory for Electric Circuit using Passive Devices Controlled, Proc. of ICEE 2008 International Conf. on Engineering Education, "New Challenges in Engineering Education and Research in the 21st Century", 27-31 July 2008, Pecs-Budapest, Hungary

Luculescu, M. & Lache, S. (2008). Using Microcontrollers in Data Acquisition Systems Designed for Human Body Vibrations Analysis, Proceedings of the 9th International Conference on Mechatronics and Precision Engineering 12-14 June 2008, IASI, Romania

*** (2008) http://www.phytec.com/pdf/datasheets/ 80C552_DS .pdf--80C552/83C552 microcontroller datasheet, Accessed on: 2009-08-09

*** (2009) http://www.wiznet.co.kr, WIZ110SR datasheet, Accessed on: 2009-08-09