File content as of revision 0:440ae480bff2:

#include "mbed.h"

Ticker Read_Port;
PortIn     DataIn(PortC, 0x000000FF);   // p21-p26
DigitalOut Reset(PTC12);
Serial Comm(USBTX, USBRX);

#define RX_BUFF_SIZE  64

int rx_write_ptr=0;
int rx_read_ptr=0;
int RX_buff[RX_BUFF_SIZE];

int Data_avl;
int Port_Data;

void Serial_Read_callback()
{
    RX_buff[rx_write_ptr++]=Comm.getc();
    if(rx_write_ptr >= RX_BUFF_SIZE)
        rx_write_ptr=0;
    
}

int Serial_Read()
{
    int temp;
    
    temp=RX_buff[rx_read_ptr++];
    if(rx_read_ptr >= RX_BUFF_SIZE)
        rx_read_ptr=0;
    return temp;
}

int Serial_Available()
{
    if(rx_read_ptr != rx_write_ptr)
        return 1;
    else
        return 0;
}

void Read_Port_callback()
{
    Port_Data=DataIn.read();
    Data_avl=1;
}

int main()
{
    int ch;
    int state=0;
    int cmd;
    int new_frame;
    int run_debug;
    Comm.baud(115200);
    Comm.attach(&Serial_Read_callback);
    
    while(true)
    {
        if(Serial_Available())
        {
            ch=Serial_Read();
            switch (state)
            {
                case 0:     if(ch == '<')
                                state++;
                            break;
                            
                case 1:     cmd = ch;
                            state++;
                            break;
                            
                case 2:     if(ch == '>')
                            {
                                state=0;
                                new_frame =1;
                            }    
                            break;
                
                                
            }//switch
            
            
        }//Serial_available
        
        if(new_frame)
        {
            new_frame =0;
            
            if(cmd == 'P')
            {
                Read_Port.attach(&Read_Port_callback,0.1);
                Reset=0;
                wait(0.01);
                Reset=1;
                run_debug=1;
            }
            else if(cmd == 'X')
            {
                Read_Port.detach();
                run_debug=0;
            }   
            
        }
        if(run_debug)
        {
            if(Data_avl)
            {
                Comm.printf("<%d>",Port_Data);
            }
        }
        
    }//while
}