32 serial ports on T4.1 for MIDI processor?

[gwpt]

I would like to build a MIDI processor for a large midi setup.
it would have 16 MIDI ins and 16 MIDI outs and ideally have a way of chaining units together to make it even larger.
what would be the best approach to getting so many serial ports working?
could I just run 32 x SoftwareSerial on GPIO pins?
or with so so many would I need some kind of external hardware?
Thanks

 

[PaulStoffregen]

After the 8 normal hardware serial ports, your best option is FlexSerial from the FlexIO_t4 library.

 

[defragster]

@KurtE did that https://github.com/KurtE/FlexIO_t4

 

[PaulStoffregen]

Kurt's extra pinout diagram is the easiest way to see which pins can be used with FlexIO.

https://forum.pjrc.com/index.php?threads/teensy-4-1-where-do-i-connect-to-use-third-spi.66144/#post-268934

Looks like 24 more pins not conflicting with the 16 pins of the 8 normal serial ports.

 

[PaulStoffregen]

The one gotcha with FlexIO is the very fast default clock speed isn't good for slow baud rates (almost anything under 115200).

See this MIDI example for how to best configure FlexIO so you get accurate MIDI baud rate.

 

[PaulStoffregen]

and ideally have a way of chaining units together to make it even larger

For expansion, I'd recommend using the USB host port, normally used with this cable. If you connect a powered USB hub, you should be able to plug in at least 4 more Teensy 4.0 or 4.1, and theoretically perhaps many more.

Teensy supports USB MIDI device on its main port. Use Tools > USB Type in Arduino IDE to configure. You'd probably configure all those expansion boards this way.

For USB host, use the USBHost_t36 library. In Arduino IDE, click File > Examples > USBHost_t36 > Interface_16x16 to get started with connecting more Teensy or other USB MIDI class compliant devices.

 

[gwpt]

Great! Thanks for the tips, ill check them out