Make changes in asf4_conf even though I think in these cases the
"peripherals" submodule is running the show.
Arduino clocks the DAC at 12MHz but uses the CCTRL setting for
clocking < 1.2MHz (100kSPS).
A fresh clock (6) is allocated for the new 12MHz clock. This matches
the Arduino value, though not the GCLK index.
Modify other settings to more closely resemble Arduino.
In AudioOut, actually clock the waveform data from the timer we set up
for this purpose.
This gives good waveforms when setting AnalogOut full-scale in a loop,
but the rise/fall of waveforms that come from AudioOut are still erratic.
Weirdly, if AudioOut limits its range even slightly (e.g., to 1000..64000)
then the erratic
Note that this will require https://github.com/adafruit/samd-peripherals/pull/26
to be accepted for the submodule update here to work.
.. otherwise, a sequence like
>>> a = audioio.AudioOut(board.A0)
>>> a.play(sample, loop=True)
>>> a.deinit()
would potentially leave related DMA channel(s) active.
This reduces the popping sound on initial playback of an audio
sample.
The M4 DAC has a pop on startup that cannot be prevented. It also
does not allow readback so current values of the DAC are ignored.
Fixes#1090
This saves code space in builds which use link-time optimization.
The optimization drops the untranslated strings and replaces them
with a compressed_string_t struct. It can then be decompressed to
a c string.
Builds without LTO work as well but include both untranslated
strings and compressed strings.
This work could be expanded to include QSTRs and loaded strings if
a compress method is added to C. Its tracked in #531.
Its slimmed down by removing the qstr and bit packing TCC info.
The trinket m0 build actually grows by 20 bytes. The arduino zero
build shrinks by 188 bytes.
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
