File content as of revision 3:2de8e4771674:

#include "mbed.h"

const int        kMaxBufferSize = 125;
volatile char    bufferSerialUSB[kMaxBufferSize+3];
volatile int     idxSerialIntUSB = 0;
int              idxSerialUserUSB = 0;
volatile int     msgSerialUSB = 0;

//RawSerial
RawSerial           serialUSB(USBTX, USBRX);    // serial PC
Serial          serial2(PC_6, PC_7); // TX, RX for udp bridge
Serial          serial7(PF_7, PF_6); // TX, RX for extension
volatile char x;
// ---------------------------------------------------
void serialUSB_int_recv()
{       
    if(serialUSB.readable()) 
        {   
        bufferSerialUSB[idxSerialIntUSB]=(serialUSB.getc());
        idxSerialIntUSB++;
        if (idxSerialIntUSB >= kMaxBufferSize) {idxSerialIntUSB = 0;}
        bufferSerialUSB[idxSerialIntUSB]= 0;
        msgSerialUSB = 1;
        }
    return;
}

void initSerial()
    {
    serialUSB.baud(115200);
    serialUSB.attach(&serialUSB_int_recv, Serial::RxIrq);
    serial2.baud(115200);  // required for UDP bridge
    serial7.baud(115200);  // required for tasmota
    //serial7.attach(&pc_recv, Serial::RxIrq);   
    
    bufferSerialUSB[0] = '\0';
    
    }
      
void sendSerialUSB(char * str)
    {
    serialUSB.printf(str);
    }

void receiveSerialUSB()
    {
    while(idxSerialIntUSB != idxSerialUserUSB)
        {
        x=bufferSerialUSB[idxSerialUserUSB];
        printf("%c",x);  
        idxSerialUserUSB = idxSerialUserUSB + 1;
        if (idxSerialUserUSB >= kMaxBufferSize) {idxSerialUserUSB = 0;} 
        }
    msgSerialUSB = 0;
    }
    
void sendserial2(char * str)
    {
    serial2.printf(str);
    }
    
void sendserial7(char * str)
    {
    serial7.printf(str);
    }