Add I2S mclk support to audiobusio.I2SOut for the Espressif port

[lookfwd]

CircuitPython version

CircuitPython 9.0.0-alpha.2 on Adafruit Feather ESP32-S3 4MB Flash 2MB PSRAM (and I guess everything on the espressif port

Code/REPL

import audiobusio
with audiobusio.I2SOut(bit_clock=board.A0,
                       word_select=board.A1,
                       data=board.A2,
                       main_clock=board.A3
                      ) as audio:
    pass

Behavior

I'm get NotImplementedError: main_clock

Description

I attempt to use ESP32-S3 with SGTL5000. I get NotImplementedError: main_clock when I try to use the I2SOut. An implementation similar to mimxrt10xx's must get ported for espressif here and the common_hal_audiobusio_i2sout_deinit function in the same file. The relevant ESP32-S3 library is here.

Additional information

No response

[dhalbert]

Note that for the SGTL5000 the MCLK input has a PLL that allows you to use any convenient clock signal that is 8-27 MHz. So for now maybe you could hook up the MCLK input to a PWM output, assuming it will run that high for Espressif.

CLOCKING
Clocking for the SGTL5000 is provided by a system
master clock input (SYS_MCLK). SYS_MCLK should be
synchronous to the sampling rate (Fs) of the I2S port.
Alternatively any clock between 8.0 and 27 MHz can be
provided on SYS_MCLK and the SGTL5000 can use an
internal PLL to derive all internal and I2S clocks. This allows
the system to use an available clock such as 12 MHz
(common USB clock) for SYS_MCLK to reduce overall
system costs.

[lookfwd]

Great idea! I used a signal generator to give it 12MHz and SGTL5000 "woke up" and started to respond in I2C, but I2S wasn't working. Turning the PLL on and doing lots of configuration is a nice interim solution.

[dhalbert]

Looks like PWM will do 12MHz:

import pwmio
p = pwmio.PWMOut(board.IO6, duty_cycle=32768, frequency=12000000)

[lookfwd]

That's great! If only it was in sync with SCLK and LRCLK, it could save us from the extra configuration and the power consumption of the PLL.

[lookfwd]

I used the Teensy Audio Adaptor Board with SGTL5000 and it beeps nicely! It even plays MIDI 🎉

with audiobusio.I2SOut(bit_clock=board.A0, word_select=board.A1, data=board.A2, main_clock=board.A3) as audio:
    init_sgtl5000()
    melody = synthio.MidiTrack(b"\0\x90H\0*\x80H\0\6\x90J\0*\x80J\0\6\x90L\0*\x80L\0\6\x90J\0" +
                       b"*\x80J\0\6\x90H\0*\x80H\0\6\x90J\0*\x80J\0\6\x90L\0T\x80L\0" +
                       b"\x0c\x90H\0T\x80H\0\x0c\x90H\0T\x80H\0", tempo=640)
    audio.play(melody)