This evolves the API from 2.x (and breaks it). Playback devices are now
separate from the samples themselves. This allows for greater playback
flexibility. Two sample sources are audioio.RawSample and audioio.WaveFile.
They can both be mono or stereo. They can be output to audioio.AudioOut or
audiobusio.I2SOut.
Internally, the dma tracking has changed from a TC counting block transfers
to an interrupt generated by the block event sent to the EVSYS. This reduces
the overhead of each DMA transfer so multiple can occure without using up TCs.
Fixes#652. Fixes#522. Huge progress on #263
Commit efbf08266b moved _estack in order to ensure 8-byte alignment
of the stack, but the address of _bootloader_dbl_tap must remain
right at the end of SRAM.
I verified by reading the source that the 4-byte-aligned address is
used for all samd21 / samd51 boards in
adafruit/circuitpython@efbf08266b. However, I only tested on
trinket_m0.
Closes: #739
1. UART: ported to ASF4. Allow rx-only and tx-only. Add .baudrate r/w property.
2. Make NeoPixel timing deterministic by turning off caches during NeoPixel writes.
3. Incorporate asf4 updates:
a. async USART driver
b. bringing Atmel START configuration closer to what we use
c. Clock initialization order now specified by CIRCUITPY_GCLK_INIT_1ST and _LAST.
4. supervisor/port.c: Move commented-out clock-test pin setting to correct location.
This introduces a new spi_flash_api.h that works for both SPI and
QSPI. The previous spi_flash functions are now called external_flash
to minimize confusion.
1. Make _extext and _sidata coincide. Old _etext location did not include
.ARM.exidx sections, which were usually absent but not always. So flash
data was copied to RAM in wrong place.
2. Use decimal constants with "K" and "M" suffixes in .ld files instead
of hex constants, to make them easier to read and check for accuracy.
There have been multiple uGame prototypes with differences in the pins
and other details. This updates the board definition to fit the final
uGame 10 design.
