A graphical tool to write your own RCX firmware !

NEW:     Ultimate ROBOLAB v.150 now available !!!!  <===

• optical RCX to RCX communication
• Nic_1 <== MOST RECENT
• Crash course
• Subsumption Architecture
• reprogramming RCX buttons
• case management  
• control 1 to 3 RC-servos  
• exploit a binaural sensor  
• recursively solving the Tower of Hanoi  
• motor-speed control
• react on signals from the LEGO remote control
• recursive functions with Ultimate Robolab
• trigonometric functions

ROBOLAB is based on the standard LEGO RCX-firmware. This very well woven basic RCX program offers many exciting features that allow easy RCX programming in nearly any environment. One of the major firmware qualities is the remarkable system-stability: it is nearly impossible to crash a running RCX. (In fact there is only one known crash that rarely appears, when kids rapidly, continuously and sometimes simultaneously press the Run and the On/Off button). The programs controlling GASTON, the humanoid robot introduced on this site, - really complex code, regarded the fact that it has been developed in a secondary school environment - are still based on the original firmware. Some firmware limitations however appeared during the programming phase:

• Because each of the involved RCX runs 10 parallel tasks and an extremely intensive IR-communication is continuously running, the slow task-switching slacken the reactions to sensor-events and cause the P-controllers to start oscillating (specially the eyebrows were affected).

• Not enough variables

• Not enough motor power-levels

• The infrared device always acknowledges a correctly received opcode through an IR-reply. Since GASTON uses a homebrew sensor that communicates its information via IR-channel, this caused some data-collusion.

• GASTON was produced for the Luxembourg Museum of Natural History, where it is shown in robotics after-school classes. While kids programmed their own robots via infrared channel, they also reprogrammed GASTON !!! Standard firmware based programs cannot be write-protected.

This unexhausted list of limitations won't affect normal RCX-programming. But, when switching to high ceiling projects, they can cause much trouble, spoiling the result. In order to continue profiting of the ROBOLAB graphical features and to allow complex RCX programming, we created "ULTIMATE ROBOLAB", a new programming tool to graphically generate code that is directly compiled to Assembler, converted to H8-opcodes and downloaded to the RCX through the normal ROBOLAB firmware-download procedure. ULTIMATE ROBOLAB automatically associates variables to their addresses, reserves memory for arrays, adds kernel-code only if required, etc; whenever possible it uses the RCX ROM-code. The results are consistent programs that unlock most of the potential of the RCX.

Some ULTIMATE ROBOLAB characteristics:

• 0x8000 - 0xCBFF :  User program area: 19k external address space RAM
• 0xCC00 - 0xEE5D : User variable area: 8797bytes in external RAM
• signed and unsigned (global and local) 8-bit, 16-bit, 32-bit integer operations and variables (addressable by names or numbers)
• single precision IEEE standard floating point operations
• pointers
• container's container
• 1D and 2D arrays
• access to standard ROBOLAB global variables (red, blue... user31 resp. 0..31)
• access to standard basic ROM-functions
• each user-program is in fact a firmware, no need to pre-install any other one
• 32 motor power levels (power value from 0..255 in steps of 8)
• the power levels may be applied to the brake mode too
• pre-emptive multitasking (H8 OCIA-handler also schedules the tasks; task-switching every ms)
• variable OCIA-interrupt time (1ms ; 3/4ms ; 1/2ms ; 1/4ms; e.a. the task-switching can be done every 1/4ms !)
• variable "powered sensor" time (possibility to drastically increase the sensor sampling rate up to 3kHz for powered and to 55kHz for unpowered sensors and to deliver slightly higher current for non-standard and homebrew sensors)
• 1/100 sec timers; ms timers
• On/Off - Run - View -Prgm button-functions
• display access to single symbols and segments; possibility to write alphanumerical characters
• infrared communication
• compatible with standard firmware opcodes 0x10 (ping), 0x63 (uploadRAM), 0xA4(uploadDatalog)...
• standard ROBOLAB compatible datalogging at the rates up to 1kHz
• subroutines may call other subroutines
• possibility to use recursive functions
• subroutines and tasks may be called indirectly through variables
• possibility to include user Assembler-code
• user can change settings concerning functions that are running in the background: display-functions, buttons, IR-communication...
• sound: standard system sound and tone
• control 1 to 3 RC-servos
• current shortcomings are: no exception handling, no out-of-memory verification.

Ultimate ROBOLAB has been officially presented at the ROBOLAB conference in August 2004 

Avant-première

We give you the possibility to test a few examples that introduce some aspects of Ultimate ROBOLAB.

1. Hello World

Comparable to standard ROBOLAB, Ultimate ROBOLAB programs start with a Begin icon and are finished with an End icon. Get ---->   hello_world.srec

2. Ohmmeter

If you download the following program, the RCX will behave as an Ohmmeter for resistors from 0..2MOhm. Connect a resistor between the pins of Sensor port 2, the display returns the resistor value expressed in Ohms. The last digit to the right of the running man is the power of ten.

The subroutine scale_Ohmmeter_display.vi  first counts the number of loops that are necessary to find out the range of the resistor-value by repeatedly dividing it by 10. Numbers smaller than 1000 are displayed as they are. The exponent and the display-scale (the place of the decimal point) are computed from the number of loops.

3. Fast datalogging

With Ultimate ROBOLAB you may do fast datalogging. The following program will store lightsensor-values at port 1 as data-points  into the red dataset at a rate of 1000 Hz. The yellow timer is used as time-base for the logging and is stored in the background to have the datalog-sets be compatible with standard ROBOLAB. Each data-point has 3 bytes.

Get  -->  fast_datalogging.srec

If you use ROBOLAB Investigator, you can upload the data. Note that the logging frequency in this example is faster than the actual sensor sampling rate of about 300Hz.

4. Using the infrared channel

Ultimate ROBOLAB gives you access to the IR-channel. You can easily set up an efficient data-exchange with the PC or a network of RCXs. Here an example how to use the LEGO remote control. Some notes about the program:

• Ultimate ROBOLAB allows you to set up your own multitasking system, but it has a powerful built-in process-scheduler. The simple RX_handler program shows how easily parallel processes can be managed. Ultimate ROBOLAB organizes everything for you.
• The RX function in the upper task verifies if the interrupt based serial machine has received a correct package, that is characterized by a few criteria known from the LEGO Mindstorms SDK. (Note that the RX function could have been added into the forever-loop of the second task. Two tasks are only used to illustrate the multitasking features.)
• The program doesn't proceed to any distinction of the pressed LEGO remote control button. But you can easily implement this. Pressing any remote button, turns on the output A for 2 seconds. The program checks if the serial packet contains opcode D2, which is the RemoteCommand opcode according to the SDK.
• If you observe the Begin icon, you notice a None label wired to it. This represents a powerful option to disable a background system task that already has a built-in RX handler. Configured as indicated, the display is no more updated automatically e.a. the running man is no longer running, if the program is executed. (However it is in a walking position that shows, that your program is actually running.)
• Get ---> simple_RX_handler.srec

5. A curiosum: compute 255 digits of PI using the Spigot Algorithm

If you download the program PI_spigot_display.srec to the RCX, it will immediately start computing. During this phase, the display shows dots. Then you will be shown 255 digits of the number PI. The main display indicates the position, the digit to the right of the running man shows returns the number.

We rebuilt the Ferrari brother's Tape Writer, presented in their famous book Building Robots with LEGO Mindstorms, Syngress. The picture shows part of what the printer wrote: hand-drawn numbers !!

Page created 26/04/2004

last update 13/02/2006

current Ultimate ROBOLAB version 1.5.0

Main Page