File content as of revision 0:17326cfa2586:

#include "mbed.h"

#define interrupt D8

void write_to_master(char);                    //function to write data to master
DigitalOut led1(LED_RED);
I2CSlave slave(D14,D15);                       //configuring pins p27, p28 as I2Cslave
Serial pc(USBTX,USBRX);
InterruptIn m2s_interrupt(interrupt);
//int m2s = m2s_interrupt;
bool read_loop = true;
void write2slave()
{
    printf("\nEntered slave code\n");
    char *data_rec = new char;
    while(read_loop){
                slave.address(0x20);
                int slave_status =1;
                printf("\nentered slave while loop\n");
             //   if(slave.receive()==3) 
                    slave_status=slave.read(data_rec,1);
                if(!slave_status){
                    printf("1 read %c from master\n\r",*data_rec);
                    read_loop = false;}
                    }
    printf("\n done \n \r");
    delete data_rec;
}
     
void led()
{
    led1=!led1;
}

                   
int main(){
   
    printf("interrupt for slave to start \n\r");
    m2s_interrupt.rise(&led);
    //write2slave();
    }