T4 Imxrt define Flexio structure.

Moved from my flexio_t4 library.
Libary was updated to see if already defined before it now defines it.

clock halved - halve blink wait count

more defs

For review - Expose alt weak func(), label displayed dump

pendablesrvreq_isr = priority 32;

add some definitions for audio

speed optimize intervalTimer

Code from :: https://community.nxp.com/thread/389002
Name the fault dump info
New weak to override :: HardFault_HandlerC()

T4 - setTX with open drain mode.

Allow the user to call setTX with the one hardware pin, and hopefully allow them to turn on Open Drain mode or turn it back off.  I don't currently have any test cases that use this, so not sure how well it works.

add nullptr check to Print.cpp - write

Make sure DONE Bit is cleared.

Swapped Core_Pin0_Padconfig and Pin1 pad config to match pin outs

Fix Bug - CSR_DONE be cleared to write the MAJORELINK or ESG bits

Page 982.
Fixes https://forum.pjrc.com/threads/54711-Teensy-4-0-First-Beta-Test?p=196233&viewfull=1#post196233
- maybe this is needed for T3x, too? too late here to check this now.

Update to my fork

t4 FLEXIO register masks are 32 bits

The FlexIO registers are 32 bits, the masks were all setup for 16 bits so the high word of registers were not updated

Drop CPU speed and TEMP when faulted offline

Update pwm.c

pwm.c: fix warnings

warning: 'flexpwm' may be used uninitialized in this function [-Wmaybe-uninitialized]
warning: 'qtimer' may be used uninitialized in this function [-Wmaybe-uninitialized]

Fix PFDs

CCmicros - micros version using Cycle counter

This fixes the PFDs for PLL2 - by default, it has totally wrong values. This sets the frequencies according to the diagram on Page 676.

The same fix is needed for PLL3 - I have code (same structure), but it does not work - Do have have any hints for me?
Is PLL3 even running? I not, can we start it? Or, if i is running - at which frequency, and  is there any non-std config?