Doesn't work with ItsyBitsy M4. and changed of QSPI code.

README.md

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+### Arduino Audio Library for Arduino SAMD21
+
+
+#### Update... an Adafruit dependency Adafruit_SPIFlash_FatFs.h is not longer available... look to some folks that have forked this repo like [gambalunga](https://github.com/Gambalunga/Audio_FeatherM0) who got it working using the updated Adafruit library.
+
+This polyphonic library allows you to play WAV files from SPI Flash and SD card to the 10bit DAC of a SAMD21 (Pin A0 on many boards). 
+Plays up to ~4 WAV files simultaneously.
+[![IMAGE ALT TEXT](https://github.com/hydronics2/SamdAudio/blob/master/screen_shot.JPG)](https://youtu.be/A0afENS1ev4 "Playing polyphonic")
+
+Adafruit has a nice tutorial on how to connect the pin to a 1/8" audio jack. The hookup [instructions are here](https://learn.adafruit.com/circuitpython-essentials/circuitpython-audio-out) (ignore the circiut python example as this library is for an Arduino sketch).
+![Adafruit image](https://cdn-learn.adafruit.com/assets/assets/000/057/479/original/circuitpython_ItsyBitsyM0AudioJackButtonPot_bb.jpg?1531328765) 
+
+The 8bit sound quality is medium quality. I was able to get up to 44.1khz using SPI flash on the Adafruit M0 boards. The quality needed to  be reduced to ~22khz when playing from the SD card.
+
+It all sounds fairly marginal at 8bit. Until there is a library with 16bit DMA output, I recommend going with a [Teensy](https://www.pjrc.com/teensy/td_libs_Audio.html) or a peripherial codec to do the heavy lifting of playing quality audio.... but hey this all sounds better than the Arduino UNO.
+
+The following Adafruit Express boards have onboard FLASH where you can store up to 2MB of sound ~30-60seconds.
+This includes: 
+* [Itsybits M0 Express](https://www.adafruit.com/product/3727) (tested)
+* [Adafruit Metro M0 Express](https://www.adafruit.com/product/3505)
+* [Trinket M0 Express](https://www.adafruit.com/product/3500) and Gemma Express no SPI Flash so SD card playing only. 
+* Adafruit M4 Express boards with the SAMD51? should work 
+
+
+Read this great description in the Adafruit tutorial for getting the WAV files onto your Adafruit M0 Express board
+https://learn.adafruit.com/introducing-itsy-bitsy-m0?view=all#using-spi-flash 
+Thanks to Tony Dicola and Adafruit for making this so easy!
+
+For the SD card example, these lines need to be edited in SamdAudio.cpp
+
+![edits sd](https://github.com/hydronics2/SamdAudio/blob/master/library_modification_SD_card.JPG)
+
+To revert back to playing WAV files from flash storage example goes like this in SamdAudio.cpp:
+
+![edits flash](https://github.com/hydronics2/SamdAudio/blob/master/library_modification_flash.JPG)
+
+
+Flash example included in the examples folder. See also SD Card Example:
+
+        /*
+
+          Audio player, non blocking.
+          read 8bit mono .wav file, up to 4 channels
+          use Audacity to convert your audio file
+          Author : AloyseTech
+
+          03/17/19: https://github.com/hydronics2/SamdAudio
+            updated to work with Adafruit Qaud Flash memory boards.
+            This will work with any SAMD21 chip using SPI flash with a little tinkering
+             - itsyBitsy M0 Express, 
+             - Feather M0 Express, 
+             - probalby M4 of abovev and trinkets 
+
+            Read this great description in the Adafruit tutorial for getting the WAV files onto your Adafruit M0 Express board
+            https://learn.adafruit.com/introducing-itsy-bitsy-m0?view=all#using-spi-flash
+            Thanks to Tondy Dicola and Adafruit for making this so easy!
+
+          if the sketch compiles and Initializes Audio player, but no sound, look in SamdAudio.cpp and umcomment these! 
+           - #include <Adafruit_SPIFlash.h>
+           - #include <Adafruit_SPIFlash_FatFs.h>
+           - extern Adafruit_W25Q16BV_FatFs memory;
+
+        */
+
+        #include <SPI.h>
+
+        #include <Adafruit_SPIFlash.h>
+        #include <Adafruit_SPIFlash_FatFs.h>
+
+        #define FLASH_TYPE     SPIFLASHTYPE_W25Q16BV  // Flash chip type.
+                                                      // If you change this be
+                                                      // sure to change the fatfs
+                                                      // object type below to match.
+
+        #define FLASH_SS       SS1                    // Flash chip SS pin.
+        #define FLASH_SPI_PORT SPI1                   // What SPI port is Flash on?
+
+        Adafruit_SPIFlash flash(FLASH_SS, &FLASH_SPI_PORT);     // Use hardware SPI
+
+        // Finally create an Adafruit_M0_Express_CircuitPython object which gives
+        // an SD card-like interface to interacting with files stored in CircuitPython's
+        // flash filesystem.
+
+        Adafruit_W25Q16BV_FatFs memory(flash);
+
+        #include <SamdAudio.h> // 
+        SamdAudio AudioPlayer; 
+
+        #define NUM_AUDIO_CHANNELS 4 //could be 1,2 or 4 for sound
+
+        #define AUDIO_BUFFER_SIZE 1024 //512 works fine for 22.05kh, use 1024 for 32khz and 44.1khz
+
+        //indicate sample rate here (use audacity to convert your wav)
+        const unsigned int sampleRate = 32000; //hz
+
+        //your wav file
+        const char *filename0 = "poem8bit_32khz.wav";
+        const char *filename1 = "sfx1_8bit_32khz.wav";
+        const char *filename2 = "sfx2_8bit_32khz.wav";
+        const char *filename3 = "sfx3_8bit_32khz.wav";
+        const char *filename4 = "sfx4_8bit_32khz.wav";
+
+        void setup()
+        {
+          delay(10);
+          Serial.begin(115200);
+          while (!Serial); // open the serial to start!
+
+          // Initialize flash library and check its chip ID.
+          if (!flash.begin(FLASH_TYPE)) 
+          {
+            Serial.println("Error, failed to initialize flash chip!");
+            while(1);
+          }
+          Serial.print("Flash chip JEDEC ID: 0x"); Serial.println(flash.GetJEDECID(), HEX);
+          // First call begin to mount the filesystem.  Check that it returns true
+          // to make sure the filesystem was mounted.
+          if (!memory.begin()) 
+          {
+            Serial.println("Error, failed to mount filesystem!");
+            while(1);
+          }
+          Serial.println("Mounted filesystem!");  
+
+          Serial.print("Initializing Audio Player...");
+          if (AudioPlayer.begin(sampleRate, NUM_AUDIO_CHANNELS, AUDIO_BUFFER_SIZE) == -1) 
+          {
+            Serial.println(" failed!");
+            return;
+          }
+          Serial.println(" done.");
+
+          AudioPlayer.play(filename0, 1);
+
+          Serial.println("Playing file.....");
+        }
+
+
+        void loop()
+        {
+          if (Serial.available()) 
+          {
+            char c = Serial.read();
+            Serial.println(c); //for debug
+
+            if ( c == 'o') 
+            {
+              AudioPlayer.play(filename1, 0); //playing file on channel 0
+              Serial.println("playing audio file on channel 0");
+            }
+            if ( c == 'p') 
+            {
+              AudioPlayer.play(filename2, 1); //playing file  on channel 1
+              Serial.println("playing audio file on channel 1");
+            }
+              if ( c == 'k') 
+            {
+              AudioPlayer.play(filename3, 2); //playing file on channel 2
+              Serial.println("playing audio file on channel 2");
+            }
+              if ( c == 'l') 
+            {
+              AudioPlayer.play(filename4, 3); //playing file on channel 3
+              Serial.println("playing audio file on channel 3");
+            }    
+          } 
+        }
+
+
+