iRacing Caution Lights

I built these lights with a 12-channel Maestro and Shift Brites. The iRacing software is a racing simulator and has an api that you can connect to. This allows apps and tools to be built to work along side the simulator. I built these lights to follow along with the race’s flags. I use a C# app to interface with the API and it sends serial commands to the maestro to change the lights. Simple, but fun.

That looks very cool, thanks for sharing!

I noticed your’re using a Mac. Do you have a USB-to-serial adapter or did you figure out how to send commands directly to the Maestro using its USB virtual COM ports?


I am sending the commands over the virtual COM ports. All of my development was done in a bootcamp installation of windows.

I did have a quick question, if you can help. Paul has helped before. The Maestro will have some sort of error at some point that causes it to stop responding. The orange light will just flash and flash. I assume it is something in the way I wired it. I don’t what triggers it as it seems to happen when not in use. i don’t know if the power is fluctuating or something. Also, I mistyped it is a 6V power supply.

Here is an image of the wiring diagram. Any help would be greatly appreciated. Thanks.

Hello, Steve.

I’m sorry you are having trouble. The next time the Maestro goes into this bad state, could you take a video of it so we can see what the blinking LEDs look like? I might be able to recognize the type of blinking and tell you what it means. Is it the same kind of blinking that happens during normal operation or is it different?

I think that the problem is probably with your power supply creating some kind of electrical noise that the USB port on your computer doesn’t like. You could try unplugging the power supply and see if the problem still happens. You could try getting a nicer power supply with a higher current capability.


The blinking is pretty fast and constant. It is just the red status LED. It is similar to normal operation, but the yellow light is completely off. it stops responding completely. I can’t even reset it with the software, I have to remove power completely for it to reset. It happens probably 5 times a week. It is always plugged in, so it is not real often. I saw this line from the User Guide “Yellow off, red blinking: A brownout reset. This occurs when the Maestro’s 5 V line drops below about 3.0 V, usually due to low batteries or an inadequate power supply.”

What type of power supply would you recommend? I plan on expanding the lights to 8 instead of 5. It will be 5 v1 shiftbrite, and 3 v2 shiftbrite. Thoughts? I am willing to try this first as I was thinking that may be the case anyway.

The current power supply is a Radio Shack version 6v 300mA. Thanks, i really appreciate the discussion and help.

-Steve Nuzum

Each shiftbrite LED can draw 60 mA when it is at full brightness, so they are probably drawing too much current for your supply when the white flag is shown (5*60 = 300). Also, that doesn’t count the amount of current drawn by the shiftbrite chips themselves.

Since you’re planning on moving up to 8 LEDs, that could draw 480 mA. I would look for a 5.5 - 9 V power supply that can provide at least that much current.

When the system gets into this bad state, what do your shiftbrites LEDs do?


Thank you, that was what I was thinking.

When the maestro goes into that state, the shiftbrites stay just as they are(color/on/off, nothing changes). So I’m thinking they draw the power and the Maestro is left out. I will switch out the power supply and see if it continues. Thanks again.

It has to be something more complicated, because you aren’t actually powering the Maestro from that power supply. You’re powering it from USB. Still I think a better power supply is a good idea, and let us know how it goes!