Introduction: Getting a LEGO RCX to Work Again

About: i do stuff, like hack 0.5" crts and nixie tubes :D

Do you have an old LEGO MindStorms RCX lying around, and want to get it to work again, but don't know how? Well, check out this tutorial!



- Windows 10 PC w/ at least one USB port

- LEGO MindStorms RCX brick (doesn't matter if it says 1.0 or 2.0)

- LEGO MindStorms serial IR tower + serial cable

- Anbear USB to serial adapter (don't use their driver disc!)

- 9V battery (to power serial tower)

- 6 1.5V AA batteries (to power RCX brick)

- RCX motors + sensors (optional, but useful)


- Prolific serial adapter drivers (scroll down and select standard version)

- firm0309.lgo (extract the .zip; this is the RCX brick firmware)

- BricxCC (click "RCX" and then "latest version")


- Knowledge of how to program in Not Quite C (there's a FAQ, manual, guide, and tutorial)


Step 1: Get the Brick to Turn On

Open the grey back of your RCX brick, put in the 6 AAs, close the back, flip the brick over, and hit the red "On-Off" button. You should see the following on the LCD display, and hear a beep:

|         ! 1 |

(The ! is a LEGO man standing.)

Great! That means the brick is working. If not, get some alcohol and a Q-tip and wipe the battery contacts, then try again. You can move on to step 2.

Step 2: Connect the Cables, and Turn on the IR Tower

Connect one end of the grey serial cable to the adapter. Plug the USB end of the adapter into your PC. Now, look for a panel on the grey back of the IR tower. Slide it down, and put in a 9V battery. Now, slide the grey panel back and connect the other end of the grey serial cable into the plug in the IR tower that's right below the sliding panel. Move on to step 3.

Step 3: Install the Necessary Applications

(Note: this step is assuming you've extracted all the .zip files in the software section of supplies.)

Install the Prolific USB > serial driver using "PL2303-Prolific_DriverInstaller_v1200.exe" in the folder you extracted the serial > USB driver to. When done, search for "device manager" in the Windows start menu, and click "Device Manager". You should see a window with some labels. There, double-click the one called "Ports (COM & LPT)". Then, right-click "Prolific USB-to-Serial Comm Port (COM3)" and select "Properties". From there, click the "Port Settings" tab and the "Advanced..." button. Then, select the "COM3" dropdown, scroll up inside the dropdown, and select "COM1". Then, click "OK" and "OK" again, this time in the previous window. Now, close the device manager. Then, run "bricxcc_setup_33810_20130220.exe" (in your downloads). After going through the setup, open File Explorer, click "Local Disk (C:)", then double-click "Program Files (x86)" > "BricxCC" and run "BricxCC.exe".

Step 4: Install the RCX Firmware

There should be tiny switch on the bottom of the IR tower. Make sure its position is to the left. Then, on a flat surface, place the tower 4-6 inches away from the black part on the top of your RCX brick. Then, run BricxCC (see step 3), and in the startup box, make sure "COM1", "RCX", and "Standard" are the three selected options. Then, click "OK". Then, click "Tools" in the top bar, and "Download firmware". From there, double-click firm0309.lgo (assuming you've extracted it from the .zip). It should now download the firmware. The LCD of your RCX brick should show a number, counting up. It should keep counting up until it reaches 1638, pause for a moment, and then, you should hear a rising beep. Now, go to step 5.

Step 5: Almost There!

You're almost there! Now, make sure you have BricxCC open, and click the "File" menu at the top, then "New", and start programming! When done, click "File" > "Save as..." > [select appropriate program format at bottom of window] > "Save" > done! To transfer a program to your RCX brick, click the "Compile" menu at the top and select "Compile", then click the "Compile" menu again; this time, select "Download and run". You're done! :D