Testing performed: I used a Particle Xenon with a HDA1334 I2S DAC.
I played a variety of mono 16-bit samples at 11025 and 22050Hz nominal
bit rates. With this setup, all the 11025Hz samples sound good.
I tested play, pause, and loop functionality.
During some runs with 22050Hz samples, there were glitches. However,
these may have only occurred during runs where I had set breakpoints
and watchpoints in gdb.
I also tested with a MAX98357A I2S amplifier. On this device, everything
sounded "scratchy". I was powering it from 5V and the 5V rail seemed
steady, so I don't have an explanation for this. However, I haven't
tried it with a SAMD board.
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.
This creates a common safe mode mechanic that ports can share.
As a result, the nRF52 now has safe mode support as well.
The common safe mode adds a 700ms delay at startup where a reset
during that window will cause a reset into safe mode. This window
is designated by a yellow status pixel and flashing the single led
three times.
A couple NeoPixel fixes are included for the nRF52 as well.
Fixes#1034. Fixes#990. Fixes#615.
We were writing with quad page program including the address (0x38)
which is unsupported by the GD25Q16C but it is supported by the
flash on the DK. So, we use the single address, quad data command
(0x32).
