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#include "audio\SoundData.h"

int freq = 8000*256;    // 频率
int channel = 0;    // 通道
int resolution = 8;   // 分辨率

const int led = 25;
void setup() {
  ledcSetup(channel, freq, resolution); // 设置通道
  ledcAttachPin(led, channel);  // 将通道与对应的引脚连接‘
  Serial.begin(115200);
}

void loop() {
  for (unsigned int i=0;i<2527766;i++) {
     ledcWrite(channel, WarOfWorldsWav[i]);
     delayMicroseconds(120);
  }
}

The maximum PWM frequency with the currently used ledc duty resolution of 10 bits in PWM module is 78.125KHz.
The duty resolution can be lowered down to 1 bit in which case the maximum frequency is 40 MHz, but only the duty of 50% is available.
For duty resolution of 8 buts, the maximal frequency is 312.5 kHz.
The available duty levels are (2^bit_num)-1, where bit_num can be 1-15.
The maximal frequency is 80000000 / 2^bit_num
In my MicroPython implementation, I'm currently working on enabling user selectable and/or automatic duty resolution and higher maxumum frequencies.

/*
  Streaming of sound data with Bluetooth to an other Bluetooth device.
  We provide the complete sound data as a simple c array which 
  can be prepared e.g. in the following way

  - Open any sound file in Audacity. Make sure that it contains 2 channels
    - Select Tracks -> Resample and select 44100
    - Export -> Export Audio -> Header Raw ; Signed 16 bit PCM
  - Convert to c file e.g. with "xxd -i file_example_WAV_1MG.raw file_example_WAV_1MG.c"
    - add the const qualifier to the array definition. E.g const unsigned char file_example_WAV_1MG_raw[] = {
  
  Copyright (C) 2020 Phil Schatzmann
  This program is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.
  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.
  You should have received a copy of the GNU General Public License
  along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "BluetoothA2DPSource.h"
#include "StarWars30.h"
BluetoothA2DPSource a2dp_source;
//SoundData *data = new TwoChannelSoundData((Channels*)StarWars10_raw,StarWars10_raw_len/4);
SoundData *data = new OneChannelSoundData((int16_t*)StarWars30_raw, StarWars30_raw_len/2);

void setup() {
  Serial.begin(115200);
  Serial.println("Start");
  a2dp_source.start("JABRA TALK");    
}

void loop() {
  if (a2dp_source.isConnected()==true) {
      Serial.println("Connected!");
      if (a2dp_source.hasSoundData()==true) {
          Serial.println("Has sound!");
        }
      else {
          Serial.println("No sound!");
          a2dp_source.writeData(data);   
      }  
    }
    else {
      Serial.println("Not connected!");
    }
  delay(2000);  
}

[FV.FVMAIN_COMPACT]
FvNameGuid         = 48DB5E17-707C-472D-91CD-1613E7EF51B0
FvAlignment        = 16
ERASE_POLARITY     = 1
MEMORY_MAPPED      = TRUE
STICKY_WRITE       = TRUE
LOCK_CAP           = TRUE
LOCK_STATUS        = TRUE
WRITE_DISABLED_CAP = TRUE
WRITE_ENABLED_CAP  = TRUE
WRITE_STATUS       = TRUE
WRITE_LOCK_CAP     = TRUE
WRITE_LOCK_STATUS  = TRUE
READ_DISABLED_CAP  = TRUE
READ_ENABLED_CAP   = TRUE
READ_STATUS        = TRUE
READ_LOCK_CAP      = TRUE
READ_LOCK_STATUS   = TRUE

[FV.PEIFV]
FvNameGuid         = 6938079B-B503-4E3D-9D24-B28337A25806
BlockSize          = 0x10000
FvAlignment        = 16
ERASE_POLARITY     = 1
MEMORY_MAPPED      = TRUE
STICKY_WRITE       = TRUE
LOCK_CAP           = TRUE
LOCK_STATUS        = TRUE
WRITE_DISABLED_CAP = TRUE
WRITE_ENABLED_CAP  = TRUE
WRITE_STATUS       = TRUE
WRITE_LOCK_CAP     = TRUE
WRITE_LOCK_STATUS  = TRUE
READ_DISABLED_CAP  = TRUE
READ_ENABLED_CAP   = TRUE
READ_STATUS        = TRUE
READ_LOCK_CAP      = TRUE
READ_LOCK_STATUS   = TRUE

APRIORI PEI {
  INF  MdeModulePkg/Universal/PCD/Pei/Pcd.inf
}

String DataBuffer[11]={{"零"},{"一"},{"二"},{"三"},{"四"},{"五"},{"六"},{"七"},{"八"},{"九"},{"十"}};
                      
//存放转化后的汉字 Unicode值
char character[40];

#include <HardwareSerial.h>

//根据字符串计算计算出来的送到串口的值
char output[50];

void setup() {
  Serial.begin(115200);
  Serial2.begin(9600);
  delay(1000);
}

void loop() {
  Serial.println("generate");

  int hh=random(13),mm=random(60);
  String timeStr="";

  Serial.print("Generate time: ");
  Serial.print(hh);Serial.print(":");Serial.println(mm);

  if (hh>9) {timeStr+="十";
    if (hh>10) {timeStr+=DataBuffer[hh-10];}
  }
  else {timeStr+=DataBuffer[hh];}
  timeStr+="点";

  if (mm==0) {timeStr+="整";}
  else
    if (mm<10) {timeStr+="零";timeStr+=DataBuffer[mm];}
    else if (mm%10==0) {timeStr+=DataBuffer[mm/10]; timeStr+="十";}
         else {timeStr+=DataBuffer[mm/10];timeStr+="十";timeStr+=DataBuffer[mm%10];}
  if(mm!=0) {timeStr+="分";}
 
    //timeStr="十二点五十八分";
  //首先输出一次Arduino 原始字符串 UTF8 的值
  for (int i =0;i<timeStr.length()*3;i++) {
     Serial.print(timeStr[i]&0xFF,HEX);
      Serial.print(' ');
  }
  Serial.println(' ');

  //将 UTF8 转化为 Unicode
    for (int i =0;i<timeStr.length()/3;i=i+1) {
      character[i*2]=((timeStr[i*3]&0xF)<<4)+((timeStr[i*3+1]>>2)&0xF);
      character[i*2+1]=((timeStr[i*3+1]&0x3)<<6)+(timeStr[i*3+2]&0x3F);
      Serial.print(character[i*2]&0xFF,HEX);
      Serial.print(' ');
      Serial.print(character[i*2+1]&0xFF,HEX);
      Serial.print(' ');      
    } 
  Serial.println(""); 

  output[0]=0xFD;
  output[1]=(timeStr.length()/3*2+3)>>8;
  output[2]=((timeStr.length()/3*2+3)&0xFF);
  output[3]=0x01;
  output[4]=0x03;
  //把字符串定义搬过去
  for (int i=0;i<timeStr.length()/3*2;i++) {
      output[i+5]=character[i];
    } 
  //计算一个校验和  
  output[timeStr.length()/3*2+5]=output[0];
  for (int i=1;i<timeStr.length()/3*2+5;i++) {
      output[timeStr.length()/3*2+5]=output[timeStr.length()/3*2+5] ^ output[i];
    }   
  
  for (int i =0;i<timeStr.length()/3*2+6;i++) {
      Serial.print(output[i]&0xFF,HEX);
      Serial.print(' ');
      Serial2.write(output[i]);
    }     
  
Serial.println(' ');
    delay(3000);
}

  SmbiosHandle = SMBIOS_HANDLE_PI_RESERVED;
  Status = Smbios->GetNext (Smbios, &SmbiosHandle, NULL, &Record, NULL);
  while (!EFI_ERROR(Status)) {
    if (Record->Type == SMBIOS_TYPE_BIOS_INFORMATION) {
      Type0Record = (SMBIOS_TABLE_TYPE0 *) Record;
      StrIndex = Type0Record->BiosVersion;
      GetOptionalStringByIndex ((CHAR8*)((UINT8*)Type0Record + Type0Record->Hdr.Length), StrIndex, &NewString);

      FirmwareVersionString = (CHAR16 *) PcdGetPtr (PcdFirmwareVersionString);
      if (*FirmwareVersionString != 0x0000 ) {
        FreePool (NewString);
        NewString = (CHAR16 *) PcdGetPtr (PcdFirmwareVersionString);
        UiCustomizeFrontPageBanner (3, TRUE, &NewString);
        HiiSetString (gFrontPagePrivate.HiiHandle, STRING_TOKEN (STR_FRONT_PAGE_BIOS_VERSION), NewString, NULL);
      } else {
        UiCustomizeFrontPageBanner (3, TRUE, &NewString);
        HiiSetString (gFrontPagePrivate.HiiHandle, STRING_TOKEN (STR_FRONT_PAGE_BIOS_VERSION), NewString, NULL);
        FreePool (NewString);
      }
    }

!if $(SMM_REQUIRE) == TRUE
  gUefiOvmfPkgTokenSpaceGuid.PcdSmmSmramRequire|TRUE
  gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmEnableBspElection|FALSE
!endif

[PcdsFixedAtBuild]
#LABZ_Start
  gEfiMdeModulePkgTokenSpaceGuid.PcdFirmwareVersionString|L"Galileo 1.0.4"  
#LABZ_End

  gEfiMdeModulePkgTokenSpaceGuid.PcdStatusCodeMemorySize|1
  gEfiMdeModulePkgTokenSpaceGuid.PcdResetOnMemoryTypeInformationChange|FALSE
  gEfiMdePkgTokenSpaceGuid.PcdMaximumGuidedExtractHandler|0x10
  gEfiMdeModulePkgTokenSpaceGuid.PcdPeiCoreMaxFvSupported|6

[BuildOptions]  
  MSFT:*_*_X64_CC_FLAGS = /FAsc /Od

GLOBAL_REMOVE_IF_UNREFERENCED const UINT16 _gPcd_FixedAtBuild_PcdFirmwareVersionString[14] = {71, 97, 108, 105, 108, 101, 111, 32, 49, 46, 48, 46, 52, 0 };

;	COMDAT _gPcd_FixedAtBuild_PcdFirmwareVersionString
CONST	SEGMENT
_gPcd_FixedAtBuild_PcdFirmwareVersionString DW 047H
	DW	061H
	DW	06cH
	DW	069H
	DW	06cH
	DW	065H
	DW	06fH
	DW	020H
	DW	031H
	DW	02eH
	DW	030H
	DW	02eH
	DW	034H
	DW	00H
CONST	ENDS

    if ((Record->Type == SMBIOS_TYPE_PROCESSOR_INFORMATION) && !FoundCpu) {
      Type4Record = (SMBIOS_TABLE_TYPE4 *) Record;
      //
      // The information in the record should be only valid when the CPU Socket is populated.
      //
      if ((Type4Record->Status & SMBIOS_TYPE4_CPU_SOCKET_POPULATED) == SMBIOS_TYPE4_CPU_SOCKET_POPULATED) {
        StrIndex = Type4Record->ProcessorVersion;
        GetOptionalStringByIndex ((CHAR8*)((UINT8*)Type4Record + Type4Record->Hdr.Length), StrIndex, &NewString);
        UiCustomizeFrontPageBanner (2, TRUE, &NewString);
        HiiSetString (gFrontPagePrivate.HiiHandle, STRING_TOKEN (STR_FRONT_PAGE_CPU_MODEL), NewString, NULL);
        FreePool (NewString);

        ConvertProcessorToString(Type4Record->CurrentSpeed, 6, &NewString);
        UiCustomizeFrontPageBanner (2, FALSE, &NewString);
        HiiSetString (gFrontPagePrivate.HiiHandle, STRING_TOKEN (STR_FRONT_PAGE_CPU_SPEED), NewString, NULL);
        FreePool (NewString);

        FoundCpu = TRUE;
      }
    }

#string STR_CUSTOMIZE_BANNER_LINE4_LEFT  #language en-US  "www.lab-z.com"
                                         #language fr-FR  ""

    if (Record->Type == SMBIOS_TYPE_BIOS_INFORMATION) {
      Type0Record = (SMBIOS_TABLE_TYPE0 *) Record;
      StrIndex = Type0Record->BiosVersion;
      GetOptionalStringByIndex ((CHAR8*)((UINT8*)Type0Record + Type0Record->Hdr.Length), StrIndex, &NewString);

      FirmwareVersionString = (CHAR16 *) PcdGetPtr (PcdFirmwareVersionString);
      if (*FirmwareVersionString != 0x0000 ) {
        FreePool (NewString);
        NewString = (CHAR16 *) PcdGetPtr (PcdFirmwareVersionString);
        UiCustomizeFrontPageBanner (3, TRUE, &NewString);
        HiiSetString (gFrontPagePrivate.HiiHandle, STRING_TOKEN (STR_FRONT_PAGE_BIOS_VERSION), NewString, NULL);
      } else {
        UiCustomizeFrontPageBanner (3, TRUE, &NewString);
        HiiSetString (gFrontPagePrivate.HiiHandle, STRING_TOKEN (STR_FRONT_PAGE_BIOS_VERSION), NewString, NULL);
        FreePool (NewString);
      }
    }

#define TYPE0_STRINGS \
  "EFI Development Kit II / OVMF\0"     /* Vendor */ \
  "0.0.0\0"                             /* BiosVersion */ \
  "02/06/2015\0"                        /* BiosReleaseDate */