Sorry, this is a backwards incompatible change.  :(  Painful but needed long-term...

https://forum.pjrc.com/threads/45518

Changed needed to support pin 45 on C3.5/6 as it is CS5 which encodes as 0x20...

As per liljaywalker member

Teensy 3.5/6 on Pin 45 have PCS5,
which the current Macro
SPI-PUSHR_PCS(n) will not work with.

Add VREF_SC_MODE_LV constants

When you do a timer.begin(650) it actually triggered 652 ms from your current time.  Did minimal update to see if delay time < 2 set to zero else decrement by 2...

Two issues:

if you called begin or begingRepeating while still in waiting queue, it would create circular state (code did not set state to waiting)

If you called begin on one in active list, it would first remove it from list, but did not update the timings for items left as the timing all rely on items before it