ATTiny85 SoftwareSerial and TinyWireS

gistfile1.txt

https://forum.arduino.cc/index.php?topic=441428.0

#include "TinyWireS.h"    
#define I2C_SLAVE_ADDR  0x25  

#include "SoftwareSerial.h"
const int Rx = 3; // this is physical pin 2 - you do not need to connect this to DFPlayer
const int Tx = 4; // this is physical pin 3 - connect to RX pin on DFPlayer
SoftwareSerial mySerial(Rx, Tx);

#define Start_Byte 0x7E
#define Version_Byte 0xFF
#define Command_Length 0x06
#define End_Byte 0xEF
#define Acknowledge 0x00 //Returns info with command 0x41 [0x01: info, 0x00: no info]

char myCmd = ' ';
int myPar = 0;

void setup() {
  pinMode(Rx, INPUT);
  pinMode(Tx, OUTPUT);
  mySerial.begin(9600); // send serial data at 9600 bits/sec
  TinyWireS.begin(I2C_SLAVE_ADDR);      // init I2C Slave mode
  TinyWireS.onReceive(receiveEvent);
  TinyWireS.onRequest(requestEvent);
  delay(500);
  execute_CMD(0x06,0,5);
}

void requestEvent()
{  
  TinyWireS.send(myCmd);
}

void receiveEvent(uint8_t howMany) {
  char c=' ';
  while (1 < TinyWireS.available()) { // loop through all but the last
    c = TinyWireS.receive();      // receive byte as a character
  }
  int x = TinyWireS.receive();    // receive byte as an integer
  myCmd = c;
  myPar = x;
}

void execute_CMD(byte CMD, byte Par1, byte Par2) // Excecute the command and parameters
{
 // Calculate the checksum (2 bytes)
 int16_t checksum = -(Version_Byte + Command_Length + CMD + Acknowledge + Par1 + Par2);
 // Build the command line
 byte Command_line[10] = { Start_Byte, Version_Byte, Command_Length, CMD, Acknowledge, Par1, Par2, checksum >> 8, checksum & 0xFF, End_Byte};
 //Send the command line to the module
 for (byte k=0; k<10; k++)
 {
  mySerial.write( Command_line[k]);
 }
}

void loop() {
  // put your main code here, to run repeatedly:
  switch (myCmd) {
    case 'p':
    case 'P': execute_CMD(0x03,0,myPar); myCmd = ' '; break;
    case 'v':
    case 'V': execute_CMD(0x06,0,myPar); myCmd = ' '; break;
  }
  TinyWireS_stop_check;
}