File content as of revision 3:32e67d121c7f:

#include "mbed.h"
#include "menu.h"
#include "parameters.h"
#include "handlers.h"

Serial pc(USBTX, USBRX);

char recv;
int state;
unsigned char cha1_pha, cha2_pha;
unsigned char cha1_amp, cha2_amp;
short spi_data;
char line_buf[4];   //line_buf[3] is used to indicate if it's empty 0 empty 1 not
int line_pt;

int main() {

    pc.baud(115200);  //config buad rate 
    state = MODE_IDLE;
    line_buf[3] = 0;
    line_buf[2] = 255;
    line_buf[1] = 255;
    line_buf[0] = 255;
    
    while(1)
    {
        switch(state)
        {
            case MODE_IDLE:
                pc.printf("%s", main_menu);
                recv = pc.getc();
                mode_idle_handler(&state, recv);
                //pc.printf("%d", state);
                break;
            case MODE_CHA1PHA:
                pc.printf("%s", cmd1);
                line_buf[3] = 0;
                line_pt = 0;
                
                while(1)
                {
                    recv = pc.getc();
                    if(recv == 13)
                    {
                        if(line_pt == 0)
                            line_buf[3] = 0;
                        else
                            line_buf[3] = 1;
                            
                        break;  //enter pressed
                    }
                    else if(recv == 8)
                    {
                        pc.putc(8);
                        pc.putc(32);
                        pc.putc(8);
                        if(line_pt == 0)
                            line_buf[0] = 255;
                        else if(line_pt > 0)
                        {
                            line_buf[line_pt] = 255;
                            line_pt --;
                        }
                    }
                    else
                    {
                        pc.putc(recv);
                        line_buf[line_pt] = recv;
                        if(line_pt < 2)
                            line_pt ++;
                    }
                }
                
                state = MODE_IDLE;
                break;
            case MODE_CHA1AMP:
                pc.printf("%s", cmd2);
                state = MODE_IDLE;
                break;
        }
        
        
    }
    
    
    return 0;
}