A little fixes for making work SAMD51 with I2S

[nekuneko]

A little fixes for making work SAMD51 with I2S

[nekuneko]

It's still uncomplete, it is needed to modify DMA utility

[ladyada]

thanks! if you can also please remove the "// <--- ERROR SAMD51" comments?

[nekuneko]

Of course, sorry for that! Probably there are more bugs ^^"

[tgvarik]

Trying to build these changes for the Feather M4 Express, I still get compiler errors about undeclared VARIANT_GCLK1_FREQ at I2S.cpp:459, among other undeclared clock-related errors. So the fixes to enableClock() and disableClock() don't work for that board.

I'm continuing to poke around and see if I can work out a fix.

[tgvarik]

Adding

#ifndef VARIANT_GCLK1_FREQ
#define VARIANT_GCLK1_FREQ (48000000UL)
#endif

to I2S.h is sufficient to get the changes to compile for the Feather M4, but that's a hack. The call to I2S.begin() then hangs, which I think is expected with current changes.

[nekuneko]

Note that VARIANT_GCLK1_FREQ constant is defined on variant.h file of the board. Please check you have an updated version of Adafruit SAMD core, I have version 1.2.9. Here you have this file location on Windows:

Adafruit Metro M4:
C:\Users\User\AppData\Local\Arduino15\packages\adafruit\hardware\samd\1.2.9\variants\metro_m4\variant.h

Adafruit Feather M4:
C:\Users\User\AppData\Local\Arduino15\packages\adafruit\hardware\samd\1.2.9\variants\feather_m4\variant.h

At the very begining of the file you must find this code:

#ifndef _VARIANT_FEATHER_M4_
#define _VARIANT_FEATHER_M4_

// The definitions here needs a SAMD core >=1.6.10
#define ARDUINO_SAMD_VARIANT_COMPLIANCE 10610

/*----------------------------------------------------------------------------
 *        Definitions
 *----------------------------------------------------------------------------*/

/** Frequency of the board main oscillator */
#define VARIANT_MAINOSC		(32768ul)

/** Master clock frequency */
#define VARIANT_MCK			  (120000000ul)

#define VARIANT_GCLK0_FREQ (120000000UL)
#define VARIANT_GCLK1_FREQ (48000000UL)
#define VARIANT_GCLK2_FREQ (100000000UL)

This file is linked during compilation (it defines all your board pinout) so that constant cannot be missing at all.

[tgvarik]

There's the problem. I'm using PlatformIO and PlatformIO is still on 1.2.3. PlatformIO doesn't have a self-service way to update, so... platformio/platformio-pkg-framework-arduinosam#8

[tgvarik]

I've done a bit more tinkering and I'm able to see some clock signals, just not the ones I expect. If I configure the I2S singleton thusly:

I2S = I2SClass(I2S_DEVICE, I2S_CLOCK_GENERATOR, PIN_I2S_SDO, PIN_I2S_SCK, PIN_I2S_FS);

...then PIN_I2S_SCK ends up getting the serial clock at the expected frequency. But PIN_I2S_FS is getting the MCLK, not the frame select clock. So now I'm digging into the port config.

(Actually, if I just use those pins as they're defined in variant.h for my board, the Feather M4 Express, I don't get any clock on any pins. But if I map them to other pins I get them. I'm not too concerned about that right now, so I'm focusing on the other issue right now.)

[tgvarik]

As written, I get the bit sync clock (sampleRate * 2 * bitsPerSample) on the pin identified by _sckPin and the master clock (sampleRate * 256) on the pin identified by _fsPin. And with my mic connected to these pins nothing comes out of the mic's data pin. However, if I add another statement after these two:

pinPeripheral(10, PIO_I2S); // just used pin 10 for testing

I then in addition to the above I also get the frame sync clock (sampleRate) on the new pin (pin 10 in this case). And if I wire up the new pin to my mic instead of the old pin (_fsPin), I get data out of my mic's data pin.

Despite seeing data coming out of the mic on the scope, I'm still getting all zeros reading it in my sketch, but this is progress of a kind.