Assembly help (related to power)


A newbie to embedded systems and I came across this project and I wanted to make my own 32x32 LED Matrix. So far, I have been researching for two days and here is the list of items I plan to order (all from Adafruit):

  • 32x32 RGB LED Matrix Panel - 5mm Pitch
  • SmartMatrix SmartLED Shield (V4) for Teensy 3
  • Break-away 0.1" 36-pin strip male header - Black - 10 pack – to attach to Teensy 3.6
  • Teensy 3.6 without headers
  • 5V 4A (4000mA) switching power supply - UL Listed –– to power the LED Matrix AND Teensy/Shield
  • Female DC Power adapter - 2.1mm jack to screw terminal block ––

    I also plan to order the following:
  • Power Enhancer Cable – so that I can plug the two usb’s into a battery pack to provide 4.2A
  • a USB to DC cable (any recommendations or can I just go with any?) to connect from Female USB to the Female DC Jack

So far, the only two question I have are:
Powering the assembly:*

  • I understand that I’ll get a cable with two plugs with the LED Panel — one of which will plug into the panel. Does the second plug remain unused?
  • I will be getting a female DC Jack (with a 5V4A DC supply) and I will plug in the fork crimps from the LED Panel cable into the back of the DC Jack.

Powering + Using SmartShield

  • Assuming my DC Jack supplies power to the LED Panel and SmartShield (using the male to female JST connection) — can I plug in the teensy to my computer while it is mains powered?
    • the reason for my question is I’ve worked with Sonoff (loading tasmota through a serial connection) and instructions explicitly say that don’t plug in the Sonoff to the computer if it is mains powered. If I can connect the Teensy to my computer using a USB cable to load the sketch while it is Mains powered through the DC Supply Jack/male-to-female JST connection?

So my connection finally will be:
LED Matrix:
Mains supply/Battery Pack Supply ––> DC Jack ––> fork crimps + included cable––> LED Matrix

Mains supply/Battery Pack Supply ––> DC Jack ––> direct plug in to male JST Cable ––> female JST cable to SmartShield/Teensy (I don’t need to power the Teensy separately if the SmartShield is powered through the JTSM connection correct?

Final question: If I’m putting this in a hat or a t-shirt, would a 4mm pitch be better or 5mm pitch be better? I am hoping that my content will be visible from short and long distances.

Thanks again for helping out… here’s hoping I learn quickly because there’s lots of helpful documentation available!

That may be a weak link, I’m not sure if any USB A cables are meant to handle 4A

Yeah, that’s fine

It won’t be as secure as using a crimp between the wire and the DC jack, but it may be fine. Just be sure the connection feels secure to you

Should be just fine. The sonoff is actually switching mains power, whereas the Teensy is powered through a DC adapter.

That’s based on personal preference and the look you’re going for. 4mm pitch uses smaller LEDs that aren’t as bright. Without knowing more I’d go for the 5mm myself.

Thanks for your input on this. I was thinking of using this USB to DC 22AWG Cable. 22AWG has an ampacity of 7A but I am not sure if the Power Enhancer Y could handle 4A. Perhaps I could use the Power Enhancer to just power the LED Matrix, reduce the brightness to 70% or so to reduce power usage, and power the Teensy via a separate battery pack.

I have seen people to do grad caps, and put these panels on t-shirts for portability, how do they usually power their panels? I am open to ideas and I have just begun my research… so if you could throw something my way, I would really really appreciate it!

Thanks, I’ll try to arrange crimps but go ahead without the crimps for now. I’ll make sure that the connection feels secure to me.

Great! Good to know that I can power the Teensy through the DC Jack and still have it connected to my computer for uploading the sketches. Really makes it easier.

Got it, thanks! I’ll order the 5mm pitch one. It is my first time with LED matrices.

Thanks for answering all my questions!