* Always clear the peripheral interrupt so we don't hang when full
* Store the ringbuf in the object so it gets collected when we're alive
* Make UART objects have a finaliser so they are deinit when their
memory is freed
* Copy bytes into the ringbuf from the FIFO after we read to ensure
the interrupt is enabled ASAP
* Copy bytes into the ringbuf from the FIFO before measuring our
rx available because the interrupt is based on a threshold (not
> 0). For example, a single byte won't trigger an interrupt.
This adds I2SOut and PDMIn support via PIO.
StateMachines can now:
* read and read while writing
* transfer in 1, 2 or 4 byte increments
* init pins based on expected defaults automatically
* be stopped and restarted
* rxfifo can be cleared and rxstalls detected (good for tracking when
the reading code isn't keeping up)
Fixes#4162
Since the datasheet cast some doubt on the strength of the "rosc_hw->randombit",
I use the SHA256 hash function to create a high quality random seed
from random values of uncertain entropy, as well as to generate a sequence
of random values from that seed using SHA256 as a cryptographically-secure
random number generator.
In practice, it produces over 100kB/s of random data which does not
have any gross problems according to _PractRand_.
Also found a race condition between timer_disable and redraw, which
would happen if I debugger-paused inside common_hal_rgbmatrix_timer_disable
or put a delay or print inside it. That's what pausing inside reconstruct
fixes.
So that the "right timer" can be chosen, `timer_allocate` now gets the `self`
pointer. It's guaranteed at this point that the pin information is accurate,
so you can e.g., find a PWM unit related to the pins themselves.
This required touching each port to add the parameter even though it's
unused everywhere but raspberrypi.
