Lego Programming and Building

1
Lego Programming and Building

• RCX Programmable microcomputer (Hitatchi
  H8/3932)
• Sensors and actuators
• Battery driven
• IR-transceiver

2
Building

• Build a SUMO-like Lego vehicle
• Control movementby motors

3
Building

• Build a SUMO-like Lego vehicle
• Control movementby motors
• Detect other vehicles by touch sensors

4
Building

• Build a SUMO-like Lego vehicle
• Control movementby motors
• Detect other vehicles by touch sensors
• Detect playing field border by light sensor

5
Competing
Table
On the table
Playing Field
Pushing is allowed
Not on the table
Remember!There can be only ONE...
6
LegOS

• Small OS to be downloaded on the RCX unit
• Runs on Linux and Windows 95/98/NT
• Not a hard real-time operating system

• Supports
• Preemptive multitasking
• POSIX semaphores
• Gives access to
• LCD-display
• Buttons
• IR communication
• Motors
• Sensors

7
LegOS System calls

• LCD-display (5 chars)
• void lcd_int (int i)
• void cputs (char s)
• RCX Button Input
• getchar()
• wakeup_t dkey_pressed()
• Task Management
• int execi(function_name)
• wakeup_t wait_event( function_name, data)
• Motor control
• motor_a_dir(enum MotorDir)
• motor_b_speed(int speed)

• Sensors
• TOUCH_1, TOUCH_2, TOUCH_3
• LIGHT_1, LIGHT_2, LIGHT_3
• void ds_activate (SENSOR)
• Miscellaneous
• sleep(int sec)
• msleep(int msec)
• random()
• srandom(int seed)
• long int sys_time
• Semaphores
• sem_wait()
• sem_post()

8
Code Provided

• Code for running a simple Lego vehicle
• Four tasks (threads)
• motor_control periodic task which controls the
  motor and takes driving commands from other tasks
• forward_run periodic task which gives commands
  for running forward or turn
• obstacle_handling interrupt driven task which
  detects obstacles
• border_handling interrupt driven task which
  detects playing field border

9
Schedule

• 16.30 - 17.00 Team selection(room
  1311) Construct your Lego SUMO vehicle
• 17.00 - 19.00 Investigate provided code(room
  1312) Program your Lego SUMO vehicle
  Download program to RCX Drive around on
  provided table Beer and snacks available
• 19.00 - XX.XX Dinner(Docs Fikarum) The great
  SUMO competition Prices More beer and
  snacks