Compatibility between 3.6 and 4.1

[Tengrii]

Hey.

I was wondering about compatibility between Teensy 3.6 and 4.1. I can see from the pinouts charts that there is a significant difference, but how big is the difference really? I am currently using pin A4 and A5 for I2C. A7 for reset, A8 for TDM and 9 for BITCLK. I would also take advantage of the fact that Teensy 4.1 has 2 TDM, where would it make sense to place the TDM pins?

Thanks for the help!

[defragster]

Check out the right pane on the audio design tool:
pjrc.com/teensy/gui/index.html?info=AudioInputTDM
and
pjrc.com/teensy/gui/index.html?info=AudioInputTDM2

Pins with names there should specify.

Also this PDF by KurtE may help fill in : KurtE/TeensyDocuments/blob/master/Teensy4.1%20Pins.pdf

[Tengrii]

Thanks for the fast answer. It did help me out a lot!!

[MichaelMeissner]

In terms of basic compatibility between the Teensy LC, 3.x, and 4.x processors, I put this in the unofficial Teensy twiki:

• https://github.com/TeensyUser/doc/wi...-Compatibility

Basically, the first serial port, the first I2C port, the first SPI port, the basic layout for power, ground is the same among the Teensies. For simple digital pins, pins 0..23 are all in the same position. Likewise, the first 10 analog input pins (A0..A9 or 14..23) are in the same position. But going more than these will involve going into various details.

Sound in particular uses different pins. If you plan to use the audio adapter, you should use revision C for Teensy 3.x and revision D for Teensy 4.x.

This page lists all of the pinouts of the various Teensies:

• https://www.pjrc.com/teensy/pinout.html

I have a google spreadsheet that tries to go into detail about the differences and commonality of the pin assignments between the LC, 3.x, and 4.x series:

• https://docs.google.com/spreadsheets...gid=1683806103

And this post that I did back before the revision D of the audio shield came out to highlight the differences for the audio pins:

• https://forum.pjrc.com/threads/57341...l=1#post214981

[Tengrii]

In terms of basic compatibility between the Teensy LC, 3.x, and 4.x processors, I put this in the unofficial Teensy twiki:

• https://github.com/TeensyUser/doc/wi...-Compatibility

Basically, the first serial port, the first I2C port, the first SPI port, the basic layout for power, ground is the same among the Teensies. For simple digital pins, pins 0..23 are all in the same position. Likewise, the first 10 analog input pins (A0..A9 or 14..23) are in the same position. But going more than these will involve going into various details.

Sound in particular uses different pins. If you plan to use the audio adapter, you should use revision C for Teensy 3.x and revision D for Teensy 4.x.

This page lists all of the pinouts of the various Teensies:

• https://www.pjrc.com/teensy/pinout.html

I have a google spreadsheet that tries to go into detail about the differences and commonality of the pin assignments between the LC, 3.x, and 4.x series:

• https://docs.google.com/spreadsheets...gid=1683806103

And this post that I did back before the revision D of the audio shield came out to highlight the differences for the audio pins:

• https://forum.pjrc.com/threads/57341...l=1#post214981

Thank you very much! It did help me a lot!! Thanks for the help!