Project questions: Teensy + SmartMatrix shield + RGB Led Matrix


#1

Hi, I asked this question on the Teensy project guidance forums but I was told that it would be best to ask someone at PixelMatix, so I am posting my (revised) question here now. Hopefully someone can help/guide me.

I want to create a 32x32 RGB LED matrix wall,
connected to the internet (Ethernet or Wifi)
to contact a webservice for new content to display.

I was thinking about using these components:

  • Teensy 3.1
  • SmartMatrix SD shield
  • 32x32 RGB LED matrix

Now, I would also like to know whether it would be possible to play raw audio files
using the Audio library together with this configuration.
I am not sure how I should connect a speaker to the Teensy,
or would I have to use the Audio Adaptor?
If so, can both the SmartMatrix SD shield and the Audio Adapter be connected?
Paul Stoffregen already answered at the forums that I could use the DAC pin for 12 bit mono output
if that was enough and for this project it is enough. The DAC pin is still accessible with this shield attached?

Apart from that. The ethernet (or wifi) connection.
Do I need another shield or adaptor for that? Any idea what I could do?
Is it possible?

And lastly, would I need two power cables to power both the matrix panel and the teensy+shield?

Thanks for the help.


cc3000 question
#2

The Audio Adapter has pin conflicts with the SmartMatrix Shield, so they can’t work together as is. The SmartMatrix SD Shield brings out the A14/DAC signal to the edge of the board. I’ve never used the DAC with a speaker myself, but you can search or ask on the PJRC forum for recommendations.

The pins are brought out on the SmartMatrix SD Shield expansion port to connect up a CC3000 wifi module, but we don’t have sample code for it and I hear there are quirks. You could use one of the cheap ESP8266 modules, but we haven’t tried this ourselves and I believe there are throughput limitations if you want to stream video. You could connect up a Linux router or Raspberry Pi. I will be focusing on the Linux router/RPi method in the near term, and hope to have a tutorial ready in the next month (or just ask me here for details, everything you need is out there already, just not documented).

If you’re going the Linux route, I’d move handling audio to the Linux computer with a USB adapter.

What content do you want to display?

One power supply is enough, the power going into the shield will power both the Teensy and the panel.


#3

Hi Louis, Thanks for the fast reply.

Actually, the 12 bit mono should suffice for this project. Do you know if I could just connect a simple USB speaker to it? Ideally it would take its power from the Teensy or SD shield as well so that I only need 1 power chord.

The reason I want Ethernet or Wifi is to update what is displaying occasionally. I want to write code that checks a webservice every 15 minutes and download new gifs or text to display and possibly new raw audio to play if there is something new. I should be able to write this code myself, but the electronics part of the project is not my cup of tea (unfortunately).

So what do I want to display? Just animated gifs, images and scrolling text. The goal is to update the SD card using the webservice and let the Teensy/SmartMatrix read the data from the SD card.

Do you think it would be possible for me with the CC3000 wifi module? Streaming video is not required for this project. Alternatively, the ESP8266 does seem rather cost-effective indeed. Can I connect it easily to the Teensy with the shield?

Thanks for your answers.


#4

I think most of your questions are better suited to the PJRC forum. I believe Paul suggested you use an amplified computer speaker. This would use a headphone plug, not USB for transmitting audio.

Using the CC3000 or ESP8266 would probably both work well. There’s probably someone out there that has hooked either up to the Teensy 3.1 and downloaded a file, which is pretty much what you need to do. I’d start by searching threads on the PJRC forum. If I had to pick one, I’d go with the ESP8266 as there are more users developing with it, and the CC3000 seems like it is going to be phased out eventually (TI has newer chipsets). There’s plenty of ports on the SmartMatrix SD Shield to connect to either module.

Good luck, and please post back if you have more questions or have something to share!