Could I use a Teensy 3.1 like a 3.2 for this project?

Status
Not open for further replies.

DaveGadgeteer

New member
I'm starting a simple project (wait for a contact closure, then play a short audio file to an I2S amplifier to a small speaker).
I have an unused Teensy 3.1 around, which I know is discontinued.
Does anyone know whether it would be usable for this? It seems a pity to just discard it, when it might be fine for such a simple project, but I've no experience to draw on for the decision. What were the flaws of the 3.1?
 
I'm starting a simple project (wait for a contact closure, then play a short audio file to an I2S amplifier to a small speaker).
I have an unused Teensy 3.1 around, which I know is discontinued.
Does anyone know whether it would be usable for this? It seems a pity to just discard it, when it might be fine for such a simple project, but I've no experience to draw on for the decision. What were the flaws of the 3.1?

Do not discard the T_3.1 :)

The only significant change to the T_3.2 was more supply current through the converter to 3.3V

They both share the same processor, feature set and pinout.
 
The bootloader chip also changed from 3.1 to 3.2. They are functionally the same. The old chip was physically larger (reducing the size made room for the large voltage regulator) and the old chip become obsolete, so we had to switch to a newer chip.
 
Can Audio Shield D be connected to work with 3.1?

The bootloader chip also changed from 3.1 to 3.2. They are functionally the same. The old chip was physically larger (reducing the size made room for the large voltage regulator) and the old chip become obsolete, so we had to switch to a newer chip.

I have an Audio Shield Rev D for Teensy 4.0.
I know the pinout is not compatible with the 3.1, but if I use discrete wires to make appropriate connections, would it likely work with the 3.1? Or would the library support need to be different in any case, making this impractical? I guess mainly it would provide an SD card interface, which could be handy for loading the sound files.
 
I have an Audio Shield Rev D for Teensy 4.0.
I know the pinout is not compatible with the 3.1, but if I use discrete wires to make appropriate connections, would it likely work with the 3.1? Or would the library support need to be different in any case, making this impractical? I guess mainly it would provide an SD card interface, which could be handy for loading the sound files.

Just get the Audio Shield Rev C. That is compatible with the Teensy 3.1, 3.2, 3.5, and 3.6. IIRC, the original Teensy 3.0 and LC did not have the appropriate sound support or instructions to run all of the audio library. Note Adafruit no longer sells the Audio shield revision C, but other distributors like Sparkfun, Digikey, etc. likely have the revision C board.

I could imagine that if you connected the wires appropriately, that you could make it work (during the development of the Teensy 4.0 before the Audio Shield D came out, Paul had a shield that went the other way, mapping the 4.0 pins to the 3.x audio shield layout). If you aren't using the audio chips at all, and just are using the sd card reader (and/or soldered memory board), it should work fine. But if you want to use the audio bits, then you need to remap the wires.

Since I have these prototype boards lying around, I would likely use them and put the the Teensy on one set of rows and the audio shield on the other, and then just solder wires to make the connection. I did a similar thing to reverse the orientation of an Adafruit Feather board.

BTW, I still have some 3.1 boards, and I used them with the revision A/B/C audio shields. AFAIK, the main thing I can't do with it is have boards like the wifi boards that need more power during startup.
 
Last edited:
I have an Audio Shield Rev D for Teensy 4.0.
I know the pinout is not compatible with the 3.1, but if I use discrete wires to make appropriate connections, would it likely work with the 3.1? Or would the library support need to be different in any case, making this impractical? I guess mainly it would provide an SD card interface, which could be handy for loading the sound files.

Well I've driven a rev D from a T3.2, so I would have thought so - its not difficult to try either, just keep the I2S bus lines short
though.
 
Best to just get the rev C audio board, which has all the signals routed to the proper places for direct connection to Teensy 3.2.

If you use the rev D audio board, you'll need to use wires for the SPI and I2S signals which are at different locations. It definitely will work if you get all the signals connected correctly and as Mark said, use relatively short wires. A few inches is fine. But you need to be really careful and meticulous to get the connections correct. Connecting to the wrong pins rarely results in hardware damage, as long as you don't let the signals touch 5 volts. But it's hard to troubleshoot. If you get really stuck, you can always show us photos of the wiring. We have a pretty good track record of spotting wiring mistakes on this forum, we good photos are shown.
 
Is there a limit to the microSD card capacity? I can't find it now, but I think I saw a limit of 8GB somewhere. The smallest microSD card I seem to have on hand is 32GB. Will that cause trouble?
 
Is there a limit to the microSD card capacity? I can't find it now, but I think I saw a limit of 8GB somewhere. The smallest microSD card I seem to have on hand is 32GB. Will that cause trouble?

IIRC it was 32GB - but that shouldn't be a limit any longer with update to SD.h using SdFat library.

Just confirmed 128GB works on SDIO and even Audio card SD with SPI on CS pin 10. And it seems even larger 256 and 512GB have been tested.
 
I recall seeing a message recently about a heavily used 1TB card with an incredible number of files taking longer to start up than SdFat allows, but apparently fairly fresh 1TB starts up quickly enough. It's on my mental list of low priority issues (haven't bought a 1TB card yet).

The 512GB card I have seems to work well. But I'll admit, I filled it up with many thousands of relatively large MP3 files copied just once, not many millions of tiny files rewritten many times.

Make sure you have Teensyduino 1.54 or later. While it was possible to run SdFat with earlier versions, the default path on 1.53 and earlier was the old Arduino SD library which supported up to only 32GB. Use 1.54 or later for large SD cards.

Ancient (2007 or earlier) tiny cards work on SPI, and on SDIO of Teensy 3.5 & 3.6, but not on SDIO on Teensy 4 & MicroMod. Those ancient cards are very rare in micro SD form factor (most cards of that era were full size). All SDHC and SDXC cards work, and pre-SDHC cards made after 2007 work too. The ancient card issue is only with the built in SDIO socket on Teensy 4.1.
 
Status
Not open for further replies.
Back
Top