Commit Graph

14 Commits

Author SHA1 Message Date
Scott Shawcroft 6857f98426
Split pulseio.PWMOut into pwmio
This gives us better granularity when implementing new ports because
PWMOut is commonly implemented before PulseIn and PulseOut.

Fixes #3211
2020-08-18 13:08:33 -07:00
Jeff Epler 011acf41c0 nrf: Ensure ticks enabled while playing audio 2020-05-13 10:40:36 -05:00
Scott Shawcroft affd3fcc2a
Clear the pending IRQ in the NVIC as well. 2020-03-13 11:16:38 -07:00
Scott Shawcroft ed5cdd7e09
Hopefully fix flash flush and hopefully audio as well. 2020-03-13 11:12:31 -07:00
Dan Halbert 8435935429 update uses of assert_pin_free; remove redundant checks 2020-02-29 15:37:32 -05:00
Jeff Epler 51af8aadb7 nrf: PWMAudioOut: 62500Hz limitation is not needed
.. and it gets in the way of some example programs, due to the way
circuitplayground library generates different frequency sine waves
2019-12-19 10:34:56 -06:00
Jeff Epler 8137ac4c49 nRF: PWMAudioOut: handle non-looping rawsamples 2019-12-17 08:59:08 -06:00
Jeff Epler 13620cc4db nRF: PWMAudioOut: fix half-speed playback of stereo samples
The "spacing" of "buffer structure" is confusing, use the "channel count"
instead.

Testing performed on nrf52840 feather:

Play stereo and mono, 8- and 16-bit, 8kHz RawSamples representing 333.33Hz
square waves.

Use both mono and stereo PWMAudioOut instances.

Scope the RC-filtered signal and use the scope's frequency
measurement function, verify the frequency is 333 or 334Hz in all tested
cases.

In the "stereo output" cases, verify both the L and R channels.  Verify
the output amplitude is the same in both channels.

In the "stereo output" cases, run a second test where the L channel's
amplitude is attenuated 50%. Verify the output amplitude is correct
in each channel.
2019-12-09 10:57:55 -06:00
Jeff Epler fae6e29546 nrf: PWMAudioOut: deactivate PWM when deinitting self
.. otherwise, when an AudioPWMOut object was deinitted without being
explicitly stop()ped, it would use up a slot in active_audio[]; the
5th iteration would create a non-working audio object which would just
buzz instead of playing the right thing.

Closes: #2203
2019-10-12 14:01:35 +09:00
Jeff Epler ef459326cb nrf: PWMAudioOut: coding style 2019-10-12 13:57:31 +09:00
Jeff Epler 77bc1ba03e nrf: PWMAudioOut: Remove the need to wait in "pause"
The original formulation was because I saw the need to avoid a transition
from playing to stopped exactly when a resume was taking place.  However,
@tannewt was concerned about this pause causing trouble, because it could
be relatively lengthy (several ms even in a typical case).

After reflection, I've convinced myself that updating the registers
in this order in resume avoids a window where a "stopped" event can
be missed as long as the shortcut is updated first.

Testing re-performed: pause/resume testing of looped RawSample and
WaveFile audio sources.
2019-08-03 08:19:25 -05:00
Jeff Epler 76f65ac694 Implement play/pause
.. and also incidentally fix a problem where a RawSample could only
be looped 131070 times.
2019-07-31 20:02:56 -05:00
Jeff Epler b72352949b PWM audio: Rename AudioOut -> PWMAudioOut, _audioio_ -> _audiopwmio_ 2019-07-29 18:39:00 -04:00
Jeff Epler a183425e00 ports/nrf: Implement audioio.AudioOut using PWM
This implements AudioOut, with known caveats:
 * pause/resume are not yet implemented (this is just a bug)
 * at best, the sample fidelity is 8 bits (this is a hardware limitation)

Testing performed:

My test system is a Particle Xenon with a PAM8302 op-amp
https://www.adafruit.com/product/2130 and 8-ohm speaker.  There's no
analog filtering between the Xenon's PWM pin and the "A+" input of
the amplifier; the "A-" pin is disconnected.  It is powered from
VUSB.

I used pin D4, which is *NOT* listed as a low-speed-only pin, but
the code does NOT switch the pin to high drive.  This is related to
an open issue for general inability to set drive level for pins
being used by a "special function" on nrf:
https://github.com/adafruit/circuitpython/issues/1270

Nothing about the code I've written should limit the usable pins.

All samples I played were 16-bit, generally monophonic at 11025Hz
and 22050Hz from the Debian LibreOffice package.
2019-07-26 07:57:11 -05:00