New breakout board - pin assignment restrictions for Teensy 4.1?

[bdurbrow]

Hi -

I'm starting the process of laying out a new breakout board for grblHAL on Teensy 4.1.

Are there any pin assignment restrictions that the Teensy driver/hardware imposes that I need to be aware of? I'm already aware of the UART pinout requirements from the iMXRT1062.

Target hardware features:
5 stepper axes with high-current drivers and opto-isolated limit/home inputs
Spindle Sync
RS485 via ISL83483 (primarily for ModBus control of spindle VFD)
High-speed RS422 data link to outboard console processor
(implemented with an ISL8490E on both ends of the link)
I2C port for external expansion modules
Header for common relay modules (found on Amazon/eBay/etc as "Arduino 4 Relay Module")
Standard grbl control switch input (cycle start, halt, probe, etc)
Any other free pins to be routed to aux opto-isolated input and output drivers as available

Thanks!

[terjeio]

Spindle PWM output is limited to 12 or 13. Spindle sync pulse input to 14.

[bdurbrow]

Thanks!