It is not often primary school children are asked to exhibit at a national exhibition, and for the twelve children who travelled to the RDS in Dublin on 12th January 2001, the experience will not be forgotten for a long, long time. The train journey from Ballina began at 06.50 and it was 22.10 before they arrived back on the same platform. The atmosphere in the RDS was new, exciting, and simply cool. Deirdre Butler, the project co-ordinator, was there too to help everybody. When we reached the RDS we rang her on the mobile to anounnce our arrival, only to hear a mobile a metre away go off .... she was right beside us! We also met Breeda Meleady, project officer with NCTE. We shared stands with some children from St. Brighid's N.S., Castleknock. We gave several demos throughout the afternoon, and to all age groups. We also had a great time looking at the other exhibits, and talking to the other project participants. Thanks to all the parents who travelled, and to Mr. Ed Gunning for giving us the loan of his laptop for our demos. Thanks to Dr. Fred G. Martin of MIT for showing us how to program in LOGO, and to LEGO DACTA also. A special thanks to Deirdre Butler and NCTE for sponsoring our visit, and to ESAT for sponsoring the Young Scientists' Exhibition, 2001.

ANOTHER GREAT TIME AT ST. PAT'S, DRUMCONDRA

The project work continued with enthusiasm, and we chose the legend of St. Patrick and Crom Dubh for the exhibition on 16th June in St. Patrick's College of Education, Drumcondra. This involved visiting some of the sites in the Ballina/Killala area, and then making, programming, and rebuilding several models, as well as some artwork, based on the story. We made lots of models and we took models of St. Patrick, Crom Dubh, Téideach's boat, Dún Briste, the Well of the Branch, the hounds Coinn Iotair and Saidhthe Suaraighe, the linnaun shee and her wheelless sliding cart as well as more bits and bobs. Leona and Denise addressed the group and told everybody what our project was about. They then thanked Deirdre Butler and the NCTE, Fred Martin as well as the parents and teachers who helped make the project a success. Dr. Pauric Travers, President of the College, then presented them with a beautiful plaque for the school, and each pupil received a certificate. Kirsty, Marie and Bryan stood at our stand with Denise and Leona and gave demonstrations. The walls and windows of the hall were covered in maps and artwork, as well as the story which came from the book, "The Stone of Truth and other Irish folk tales" by Douglas Hyde, ISBN 0 7165 2344 2. We all got a quick look at the great projects from the children in the other 12 schools, and it was a fantastic day. We look forward to doing the project again next year. Denise and Leona will have gone to Secondary School, but we will have a new second class.

The program for the RCX is written on a PC. 
LOGO commands are sent from the Yellow Brick Logo application on a PC via cable, to the tower -- the wedge-shaped black box in the image on the left. The tower is a transceiver. It "talks" to an RCX within range, and if one is  found, the program will start to "beam down" or download. 
Since the PC-to-RCX connection is wireless, the robot can't hurt the PC.

THE RCX WITH MOTORS AND SENSORS ATTACHED

An RCX has 3-outputs and 3-inputs. 
The RCX shown on the left has two motors attached to outputs A and C. Nothing is attached to output B in this shot. A touch sensor is attached to input 1 and another is attached to input 3. A light sensor is attached to input 2. A transceiver (infrared communications port) is located at the end of the brick nearest the light sensor. A transceiver is a transmitter and receiver in one unit. A small LCD panel, surrounded by RCX control buttons coloured red, green, grey and black, shows what's happening when a program is running.

A TOUCH SENSOR

 Note the yellow button which is a push-button switch like that on a door-bell. Note that four of the six studs on top have electrical contacts.

What has happened? 

The RCX has read the "pressed" and "released" states and shown these as a low number and a high number. Because it shows just 2 numbers we call it a digital device. A robot could use this sensor to turn if it touches a wall.

A LIGHT SENSOR

Note that the light sensor has a light transmitter and a light receiver to measure the light reflected back. A cable comes from the light sensor body to an electrical plate.

What has happened? 

The light sensor on the RCX has received different levels of light and the RCX has shown these as different numbers. Because the light sensor shows several different levels to the RCX we call it an analogue device.

THE ROTATE SENSOR

The rotate sensor can be useful for telling the RCX, for example, how much a robotic arm has turned. 

The temperature sensor can tell, for example, if a motor is over-heating and the RCX can shut down everything. 

Both are analogue devices.

THE TEMPERATURE SENSOR

THE YELLOW BRICK  LOGO SCREEN

To program the RCX, we open the Yellow Brick Logo application, and the Yellow Brick Logo screen above appears. We type our LOGO commands in the three white areas. We look at each of the white areas in the next sections.

Commands typed in the Yellow Brick Logo Command Center, followed by ENTER,  go straight to the tower to be sent to the RCX.

Place the RCX near the tower, with both tranceivers facing each other and attach motors as for previous tests. Turn on the RCX by pressing the red On-Off button, and try the commands shown below.

THE PROCEDURES WINDOW

A LOGO procedure is a list of instructions written on lines following a line beginning with to and before a line with the word end on its own.
The following procedure, when downloaded, could be used to turn on motors attached to outputs A and C, and switch both off after 2 seconds.

THE RUN BUTTON LINE

After a procedure is written, it can be downloaded to the RCX by placing its name in the Run Button Line and clicking the Download button.
If we type turnon-a-c in the Run Button Line after we have taught LOGO to turnon-a-c, the procedure turnon-a-c will be downloaded to the RCX when we press the Download button. The program will not run on the RCX until we press the green Run button on the RCX. Press Run again to stop the program. We could turn off the RCX and next day, when turned on, it would still remember how to turnon-a-c, unless we downloaded a new procedure.

We can save procedures by going to File, Save Project As, and giving the procedure in the Procedures Window a name. To use these again we go to 

Write the following procedure and download it:

Press Run on the RCX, and the motor attached to output A turns on, and reverses direction each time the yellow button of the touch sensor attached to input 1 is pressed. Press Run again to stop the program running.
Now try [a, off c, onfor 10] instead of [rd] to see what happens.

Write the following procedure, taking care with the spaces, and download it:

Press Run on the RCX, hold the light sensor in your hand with its light beaming down on the RCX and see if the RCX detects whether it's over a yellow set of studs on the RCX or not. It should beep just like the scanner at the supermarket checkout, but if not, try changing the number 750 to a different number. This procedure is recursive, because in the third line, see-it calls itself. It will just keep testing sensor attached to input 2.