Smart matrix shield for teensy 4, comms from processing

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domugraphic

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Hello people, I'm new!

After eyeing the teensy for audio projects for some time, I came across a project the other day that made me decide to take the plunge and order a teensy 4.0 / smart matrix shield / RGB LED panel (hub75)

The project is here:

https://www.creativeapplications.ne...-matrix-display-tutorial-document-1-workshop/


and describes the use of processing to send screen data to a teensy 3.x / smartmatrix shield for 3.x. It gives code examples on both the processing and arduino code side of things, which I understand reasonably clearly (I'm experienced in processing-ish) however electronics and physical computing I'm completely new to.

I presume data is sent from processing to teensy via serial (could be wrong) but I'm not sure how one does that, the link does not describe the physical connections. More importantly I'm wondering whether (with the minimal changes to code required) whether the same combo but using teensy 4.0 / matrix shield for 4.x is capable of the same kind of communication. Ive held off ordering the £150 worth of equipment for fear that I won't actually be able to drive the shield or panel from processing, due to not understanding the way the two communicate and any possible differences that may stop a 4.x doing the same thing they're doing with the 3.x

I could go with t3. X and the previous version shield, however given the superior power of the newer teensy (and that I'm aiming to also use the board for intensive audio applications) I'd rather verify that I can indeed use the 4.x and buy all the stuff pertaining to that generation of board.

This is possible right? Any big issues I should be aware of? How are processing and the teensy connected in either case? I could use Windows 10 or raspberry pi 3b+ (ideally raspberry pi)

I've searched the smartmatrix community forums but find no answer and thought maybe it's more sensible to sniff around here instead. Sorry for length of the post, and doubly so if this information is obvious or easily found (I've read so much my eyes hurt already)

On a further note (though this is not teensy related) there is a Hat for the raspberry pi which uses the same arduino library, is it possible to run processing on the pi and have it transmit the canvas directly (via the smartmatrix hat) to the LED panel, bypassing teensy altogether? Just curious, I'm still more interested in using teensy given my interest in the audio hardware side of things, but if anyone knows about the pi driving these HUB75 panels using the smart LED / smart matrix library then please chip in, I'd be happy to learn.

Yeah, let me know if I can go ahead and order the teensy 4, shield for 4.x and panel without having to worry! (using processing to generate the imagery is a must for me.) And what kind of cabling I'd need to do between the processing host and the teensy board.

Many thanks in advance, and I'll look forward to perusing the forums and getting to know some of you. Cheers!
 
Okay upon reading more it seems that alot of the time noone even mentions the 4.0 / 4.1 even in recent times.

Would I be better going for the 3.x for my LED and also audio experiments?
 
Okay upon reading more it seems that alot of the time noone even mentions the 4.0 / 4.1 even in recent times.

Would I be better going for the 3.x for my LED and also audio experiments?

The Teensy 4.x shield only started shipping in December of 2020, so the user base is likely ramping up. I ordered one of the Teensy 4.x shields and it now works for me running some of the demos. I had some teething pains, getting the pins and cables set up. I originally used the Teensy 4.0 and I moved up to the Teensy 4.1. With the Teensy 4.1, I needed to solder it so only the first 14 pins on each side connected the board. With the Teensy 4.1, you do have to cut off one of the mounting holes to allow the longer Teensy 4.1 to be used. Other than run some demos, I haven't done much with it.

Note, the pinout for the Teensy 4.x processors is different from Teensy 3.x, both in terms of the the smartmatrix shield, and in terms of the second serial/i2c/spi pinouts. This might mean you will need to change the pin uses in the Teensy 4.x.

Unfortunately, in the Teensy 4.x shield, you can't do both audio input and output using the default pins. This is because the smartmatrix shield needs to use either pin 7 or pin 8 (pin 7 is the default pin for I2S output, pin 8 is the default pin for I2S input). I believe there are some alternative I2S pins that you could use. You might need to do some calls to change the defaults, and if you use the audio shield, don't connect pin 8 and instead use a wire to an alternate pin
 
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I see, thanks for the heads up. This leaves me in a tricky situation.as I'm not familiar with teensyduino at all and so am not sure if it's folly for me to attempt to port the linked sketches or not. I'm not even sure it's necessary as surely the library has changed along with the shield, along with any differences between 3.x and 4.x.
In addition it seems I'll be paying significantly more (in the UK) to get hold of a 3.x + shield for 3.x for a step down in procesing power. The only stock I've seen over here are 4.x shields..

Just out of interest, if you've only run a few demos what prompted you to upgrade to the 4.1?

I will attempt to contact the people responsible for the workshop again and hope for some guidance.

Still, I wonder what method one would use to connect the sketch output of a computer running processing over to the teensy / shield / led side (irrespective of the pin etc differences between 3 and 4.)

If anyone with half a clue (ie not me) fancies taking a look at the link I shared and possibly shedding some light on the communication method, again I'd be heavily endebted.
 
I see, thanks for the heads up. This leaves me in a tricky situation.as I'm not familiar with teensyduino at all and so am not sure if it's folly for me to attempt to port the linked sketches or not. I'm not even sure it's necessary as surely the library has changed along with the shield, along with any differences between 3.x and 4.x.
In addition it seems I'll be paying significantly more (in the UK) to get hold of a 3.x + shield for 3.x for a step down in procesing power. The only stock I've seen over here are 4.x shields..

Just out of interest, if you've only run a few demos what prompted you to upgrade to the 4.1?

I will attempt to contact the people responsible for the workshop again and hope for some guidance.

Still, I wonder what method one would use to connect the sketch output of a computer running processing over to the teensy / shield / led side (irrespective of the pin etc differences between 3 and 4.)

If anyone with half a clue (ie not me) fancies taking a look at the link I shared and possibly shedding some light on the communication method, again I'd be heavily endebted.

The Teensydunio 4.1 has a built-in sd card reader, and some of the demos use that to hold images. Going down the road, the Teensy 4.1 has two pads underneath the Teensy that you can solder surface mount chips to add either one chip with more volatile RAM (2 megabyte/16 megabit) and one chip with non-volatile RAM (1 megabyte/8 megabit), so that you can have more memory for processing, and an additional place to store things that are saved between power outages. Presumably if you are getting into heavy image processing, you may want to use that volatile RAM as a buffer (the RAM is bigger, but slower than the normal RAM).

If your soldering skills aren't up to doing SMT soldering, there is a company that sells a fully loaded Teensy 4.1. Note, you may want to talk with them to not attach the back 10 pins on each side (or attach female headers), since those pins would interfere with attaching the Teensy 4.1 to the smartmatrix board:

The Teensy 4.1 has pins for setting up an ethernet connection, that you can use to connect to other computers or the internet at large via normal TCP/IP networking. I haven't used it yet.

The simplest communication method is just to use the USB connection. At the simplest, you can just use it a serial device between the computer and Teensy. But you can also have the Teensy do more complex things. For example, you can configure the Teensy to act as USB audio, USB midi, a keyboard/mouse. Currently there is work to make Teensy act as an USB disk. For the USB connection, you don't need any special pins. Note, the Teensy 4.x can operate its USB connection at USB 2.0 speeds, while Teensy 3.x are limited to USB 1.0 speeds.
 
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