OnWorks favicon

firmdl3 - Online in the Cloud

Run firmdl3 in OnWorks free hosting provider over Ubuntu Online, Fedora Online, Windows online emulator or MAC OS online emulator

This is the command firmdl3 that can be run in the OnWorks free hosting provider using one of our multiple free online workstations such as Ubuntu Online, Fedora Online, Windows online emulator or MAC OS online emulator



firmdl3 - A firmware downloader for the RCX. Version 3.0.


firmdl3 [options] srecfile


This manual page documents the firmdl3 kernel download command.

firmdl3 is a program which is used to download the brickOS kernel (firmware). firmdl3
Supports single and quad rate downloading (quad-rate is default).

Quad-rate downloading is a feature that significantly reduces firmware download times. It
is implemented on top of a fast serial protocol that has a 2x baud rate with no
complements or parity bits. The fast protocol is enabled by a short firmware stub that
reconfigures some control registers and tweaks some ROM program state. Once the firmware
stub is downloaded and executed, the ROM responds to the fast serial protocol, which the
downloader then uses to transfer the actual firmware file. Because the initial firmware
stub is small, all but the most trivial programs see a download time improvement when
using quad-speed downloading.

The caveat to using quad-speed downloading is its sensitivity to lighting conditions.
Getting quad-speed downloading to work right might require some trial and error. In
addition to avoiding harsh lighting conditions, it is important to place the RCX around
4-12 inches from the IR tower.


This program follows the usual GNU command line syntax, with long options starting with
two dashes (`-'). The options supported by firmdl3 are:

-h, --help
Show built-in help (summery of options)

-f, --fast
Use 'fast' (4x) download algorithm (default)

-s, --slow
Use 'slow' (1x) download algorithm (Use if experiencing download problems)

Specify serial serial tty where IR tower is connected.

NOTE: The environment variable RCXTTY may be used in place of -tty

Enable debugging. (Mostly displays raw bytes).


firmdl3 will respond to the environment variable RCXTTY. This should be set to the serial
device to which the IR tower is connected. Use of RCXTTY is equivalent the using the -tty
command-line option.


firmdl3 is a simple command to use. The following examples show most of the uses.

Ex1: download the brickOS kernal to ttyS0.

$ firmdl3 -tty=/dev/ttyS0 /usr/lib/brickos/brickOS.srec
Transferring "Fast Download Image" to RCX...
Transferring "/usr/lib/brickos/brickOS.srec" to RCX...

Ex2: download the brickOS kernal to ttyS1 (set env var 1st).

$ export RCXTTY=/dev/ttyS1
$ firmdl3 /usr/lib/brickos/brickOS.srec
Transferring "Fast Download Image" to RCX...
Transferring "/usr/lib/brickos/brickOS.srec" to RCX...

Ex3: download the brickOS kernal using slow protocol (assumes RCXTTY is already set).

$ firmdl3 --slow /usr/lib/brickos/brickOS.srec
Transferring "/usr/lib/brickos/brickOS.srec" to RCX...

NOTE: the missing indication of the "Fast Download Image" being sent.

We'll leave the experiment of running firmdl3 with --debug set as an exercise for you our
reader... (You really interested in seeing all the bytes fly by? ;-)


(excerpt from brickOS HOWTO)

delete firmware failed
Because of a limitation in the Lego firmware, firmdl3 cannot delete LegOS.
Instead, before downloading the new firmware, you must first stop the old LegOS
program, and then hold down the Prgm button while hitting the On/Off switch. This
will delete the old LegOS firmware, allowing a new download. Alternately, if you
see no green light on the IR box and get this error message, it may indicate you
have a dead battery in the IR tower.

/dev/ttyS0: Permission denied, com1: Permission denied, or a similar message.
The first part of the error message is the output port that firmdl3 is trying to
use. This can mean two things. Either you have specified the wrong device or you
have specified the correct device but do not have permission to access it. If it is
an access problem, speak to your sysadmin. If not, you can use the --tty argument
to specify another device. For example, to specify the standard device under linux,
try ´firmdl3 --tty /dev/ttyS0´. Under cygwin, you probably probably want to use
´firmdl3 --tty com1´. If you discover that this is the case, you may wish to
recompile firmdl3 to make your setting the default.

/dev/ttyS0: Input/output error or a similar message.
You forgot to plug the tower in, most likely.

unlock firmware failed
This indicates that there was a slight corruption in the download. Clear brickOS
and download it again.

no response from RCX
This error should be called "you forgot to turn on your RCX, moron." If I hadn't
done it about 10 million times, I'd submit the patch to change the error myself.

If firmdl3 gives you repeated problems, you may want to try using the --slow argument,
which will make your download much slower but can correct for certain errors caused by
ambient light.

Use firmdl3 online using onworks.net services

Free Servers & Workstations

Download Windows & Linux apps

  • 1
    Image Downloader
    Image Downloader
    Crawl and download images using
    Selenium Using python3 and PyQt5.
    Supported Search Engine: Google, Bing,
    Baidu. Keywords input from the keyboard
    or input from ...
    Download Image Downloader
  • 2
    Eclipse Tomcat Plugin
    Eclipse Tomcat Plugin
    The Eclipse Tomcat Plugin provides
    simple integration of a tomcat servlet
    container for the development of java
    web applications. You can join us for
    Download Eclipse Tomcat Plugin
  • 3
    WebTorrent Desktop
    WebTorrent Desktop
    WebTorrent Desktop is for streaming
    torrents on Mac, Windows or Linux. It
    connects to both BitTorrent and
    WebTorrent peers. Now there's no
    need to wait for...
    Download WebTorrent Desktop
  • 4
    GenX is a scientific program to refine
    x-ray refelcetivity, neutron
    reflectivity and surface x-ray
    diffraction data using the differential
    evolution algorithm....
    Download GenX
  • 5
    PSPP is a program for statistical
    analysis of sampled data. It is a free
    replacement for the proprietary program
    SPSS. PSPP has both text-based and
    graphical us...
    Download pspp4windows
  • 6
    Git Extensions
    Git Extensions
    Git Extensions is a standalone UI tool
    for managing Git repositories. It also
    integrates with Windows Explorer and
    Microsoft Visual Studio
    (2015/2017/2019). Th...
    Download Git Extensions
  • More »

Linux commands