Astropixels, assemble!

The Astropixels come as a ready to use kit, just connect the cables and give them some power! I have previously offered unsoldered sets for a small discount, but few people chose that option and by offering the full kit I can make sure every setup is properly tested before they leave me.

The kit comes with everything you need to light up an R2 dome. This includes 2 FLD boards, a RLD board, 2 PSIs, and 3 HPs. Also included are all the cables you need to route around the dome. Older kits had HPs with wires soldered on, newer kits have HPs with three pin headers. This made my job of assembly a lot easier and the mounting options a little better. If you are new to droid building, you can get a list of common terminology on the main droid wiki:

The recommended connections are as follows

  • Breakout board -> RLD = 1 x 10cm
  • Breakout board -> FLD = 1 x 30cm extension + 1 x 10cm
  • FLD -> FLD = 1 x 10cm
  • Breakout board -> FPSI = 1 x 30cm extension + 1 x 20cm
  • Breakout board -> RPSI = 1 x 30cm
  • Breakout board -> THP = 1 x 30cm extension + 1 x 10cm
  • Breakout board -> RHP = 1 x 20cm
  • Breakout board -> FHP = 1 x 30cm extension + 1 x 30cm

All outputs are clearly marked on the breakout board, just make sure that the cables are the correct way round. Typical colour standards are black for ground, red for 5v, and white for signal/data. Getting this wrong could result in damage to the light board.

The main breakout board is designed to mount on the back of the RLD, there is a 3d printable spacer on the Astropixels Extras post, or you can just use a stack of nylon washers or similar. Mounting the board here and running the cables as above should mean that everything can be kept neat and tidy against the inside of the dome.

The logics follow the same mounting hole pattern as the old teecees, so most club surrounds will work without any issues. The PSIs are also the same diameter so will fit in most of the mounts available. The Astropixels Extras page has files for printing or cutting bezels for the logics too. I recommend at least putting a clear acrylic layer between the light boards and the logic surrounds to stop little fingers getting in there. To avoid warping the board you can put a nylon washer between the layers.

Breakout board

For powering the lights, you can test using a usb cable from the computer to the ESP32, but do not power this way when inside the dome, the current consumption can get too high and cause a brown out. I recommend a decent 5v buck converter or similar (with at least 1A of current) and to power it via the screw terminals.

Interfacing with the system is done using one of the three sets of headers to the right. Top is i2c, with the pins being Clock, Data, +ve, and Ground. Then below that are the two serial interfaces with the pins Tx, Rx, +ve, and Ground. By default the code will be programmed with i2c enabled on address 0x0a. More details on how to trigger effects can be found in the ReelTwo documentation.

All boards are tested before shipping, but if you have any issues or questions, just give me a shout. You can also join our Droidbuilders Discord Server and chat more real time (and with other builders)

If you want a set of Astropixels, my store can be found here:

If they are currently sold out, you can sign up for notification on the UK Droidbuilders Portal here:

This Post Has 15 Comments

  1. Derek Kastning

    Are these plug and play if I get the assembled kit? And how do I order??

    1. dpoulson

      Sorry, I didn’t get a notification about a comment, so only just seen this.

      If you order the assembled kit, then you just add power and they’ll work.

      You can sign up for notifications on the Droidbuilders UK Portal ( Just go to the parts run section and find astropixels, then you can subscribe for notifications.

  2. Rick

    Hi Darren,
    just recently purchased a set of ‘Astropixels’ & they are fantastic! (have tested it via USB cable), But, not being electronically minded, I’m not too sure how to power it or how to interface it, can it be powered using a 5v power bank (like those to charge a mobile phone?
    I see from one of your photos (the one with the 5 red buttons) that you don’t seem to be using the screw terminals for power, how are you powering this & how are the other wires (interfacing???) configured?
    Many thanks.

    1. dpoulson


      Thanks for the response! 😀

      Whilst you can power them from a USB power bank, sometimes USB power may not be enough (max of 500mA, tho you can get higher ones but not sure if they need to communicate with the device to draw more), so I recommend powering them from a 5v buck converter hooked up to either the main power through a slip ring, or from a standalone battery in the dome. (maybe a 12v one?). The test bed I’ve got is just powered from the USB output of a Raspberry pi as its just for messing with.

      That being said, if you want to keep it simple, then a usb power bank will be good enough if you aren’t triggering effects via a control system. Worst that can happen is a brown out and the lights reset. My test bed browns out quite often with certain effects that ramp up the current consumption.

      If you work on a draw of 500mA @ 5v, then you can work out the size of battery you need. A powerbank for example that is rated at 10000mAH would (if they’re telling the truth and it isn’t a cheap chinese one sold using lies) would last about 100 hours.

    2. dpoulson

      The other wires like the serial and i2c can be ignored unless you’re hooking it up to your control system to trigger effects. For basic operation all you need is power.

    1. dpoulson

      It will only draw the amps that it requires, so you can set it to anything over about 1A.

      That being said, it may be that you’re confusing constant voltage mode, and constant current mode. You want it in constant voltage mode, with the voltage set to 5v. I’m not familiar with that particular buck converter and as usual the instructions for them tend to be quite lacking.

  3. Brian

    Thanks. I’m sure I am confused 🙂 Your are right my buck instructions were terrible. But, I figured out how to change the output voltage. Set to 5 and seems to work great.

  4. Brian

    Another question I have: How do I get the holo projectors to light up when just plug and play? Or is that something I might need to re-program to do. Basically, I have the dome as a stand-alone display piece right now. Thanks.

    1. dpoulson


      So by default the HPs will come on for a random amount of time for a random period. Something like between 60 and 180 seconds for 10-20 seconds. I’d have to dog through the code for the actual times, but that’s approx.

      It can be changed in code for different durations.

      If you have it hooked up to a control system you can also trigger effects using serial or i2c.

      Something you might want to look at is a firmware someone else has done that adds WiFi to it and allows you to use the rtouch phone app to trigger effects, including the HPs.

      Not messed with it personally, but heard good reports about it.

  5. Brian

    Great thanks. Yes later I plan on gettin fancy. But I have just a stand-alone dome for now and wanted to keep it simple. Thanks for the quick response. I will check out that link.\

  6. David DeMarchis

    Hi Darren, I bought a set of astropixels second hand from another builder. I have them installed and up and running, but I’m wondering about triggering affects on them, such as changing colors on the logics. I understand it will require serial or i2c commands, but I don’t see any documentation on how to do this. Can you point me in the right direction? Many thanks.

  7. Richard

    Hi there,
    Please could you advise if you ship to New Zealand?

    1. dpoulson

      As per the product page, I ship world wide.

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