Hi Mr. Erik,

Thank you and happy for the response. Sorry for the bad code readability. Yes, my goal is light an LED through a command through serial terminal. Yeah, i expected that would be wrong, the '1' part. And i made sure that i use character '1' to poll. I used serial.scanf() as well as serial.getc();. But the goal hasn't been achieved. What are the connections? Did i miss something in connections part and minicom settings?

My minicom settings are: Baud rate: 9600, 8 bits, No parity, 1 stop bit. 9600 8-N-1. and the device after 'dmesg' detected as USBACM device with all PID,VID. So the device was ttyACM0. Connections : D+ , D- of USB connector to D+ and D- of mbed. GND, VUSB to VCC. And the respective connection to LED which i'm lighting.

And in USBHID, the problem with the script that should be running on the host is not available for Linux( my OS Ubuntu 12.04) and even for Windows too. So i couldn't check the possibilities of getting this done with USBHID. It seems as a mere preferable and possible solution to my problem, but i couldn't able to do with that. Any further way in that is possible?

I would first try to add a serial.printf, and see if you receive that on your PC. You need the D+ and D- pins, otherwise it really cannot work.

If printf works fine, see if you can change the transmit settings. Not sure if minicom by default sends a '\r' or '\n' as enter.

Hmmm, as I can see, you are using virtual serial USB, but the "Serial serial (USBTX,USBRX) is for the mbed serial port though the mini USB. Try to use the MBED com port instead. You can allso define a faster bitrate with serial.baud(115200) if you want. For using USBserial (virtal com), you have to use :

USBSerial serial;

instead. I hope you understand, what I tried to tell you. English is not my primary language, and I have sometimes troubles to clear myself ;)

RGDS

Ok, just some update. I unintentionlly made a mistake while deleting some stuff from the code. A bracket wasn't at the right position. Now this piece of code works, but WITH MBED com port, not with the USBserial. I was not able to make the code work properly. So far I used USBserial only with RTOS, and that worked for me, but with the classic type of programming, I'm not able to make it run. I'm able to read 1 character, after that the code freeze. But for now, I hope this will be good for your project. I will do some more debugging, and post a new piece of code.

RGDS

#include "mbed.h"
//#include "USBSerial.h"

//Virtual serial port over USB

DigitalOut led1(LED1);
Serial serial(USBTX,USBRX); //uncomment this for serial comm via mini USB - MBED
//USBSerial serial; //use this for a virtual com port on D+ & D-

char ser_buf[10],i,data_OK;

void Serial_parser()                           // Parser function for Data in the Serial buffer
{

    if(data_OK) { //if everything is ok, data are available

        switch (ser_buf[0]) {

            case 'L':
                if((ser_buf[1]=='e') && (ser_buf[2]=='1')) { //The command for turning led on is "Le1
                    led1 = 1;
                }
                if((ser_buf[1]=='e') && (ser_buf[2]=='0')) { //the command for turning led off is "Le0"
                    led1 = 0;
                }
                break;
            default:
            serial.printf("Command unkonwn \r\n");
        }
        data_OK = 0; // we did what we have to do
        for(int x=0; x<10; x++) ser_buf[x] = 0; //clear buffer
    }
}


void Serial_get_data()                   // Aquiring serial data
{
    if(serial.readable()) {  //if data are available - uncomment this for mini usb MBED
//      if(serial.available()) { //use this for virtual com port on D+ & D-
      
			ser_buf[i]=serial.getc();

        if (ser_buf[i] == '\r') { //if CR is recieved, we ended the sentence
            data_OK = 1; //we have something to parse
            i=0; //reset the counter

            Serial_parser(); //call the parser function
        } else {
            serial.putc(ser_buf[i]);
            i++;
            if(i>10) i=0; //we need only a few characters to turn a led on or off
        }
    }
}

int main(void)
{
    serial.attach(&Serial_get_data);
    
    while(1) {
			
    }

}

Finally I got it working, but is not interrupt driven yet, but it works. I'll try with interrupts tomorrow. But if you hook your Virtual USB port, and type Le1 or Le0 into your terminal program, you will be able to turn on or off your led. Hit return for make the changes available.

RGDS

#include "mbed.h"
#include "USBSerial.h"

//Virtual serial port over USB

DigitalOut led1(LED1);
DigitalOut led2(LED2);
DigitalOut led3(LED3);
DigitalOut led4(LED4);
USBSerial serial; //use this for a virtual com port on D+ & D-
Ticker t;


void Hartbeat()  //just for debugging  - to see if the program hangs
{
    led2 = !led2;
}

char i = 0;
char buf[30];


int main(void)
{
    t.attach(&Hartbeat,1.0);      //we periodically call the hartbeat function
    while(1) {
        if(serial.available()) {      //if there are data in the rxbuffer
            led3=!led3;                 //flash a led, to tell, that data is recieved
            buf[i]=serial._getc();        //store the character into buffer
            i++;                            //increment buffer index
            if (buf[i-1] == '\r') {       //if the last character was CR
                led4=!led4;                 //let me know eith a led
                if(buf[0]=='L' &&  buf[1]=='e' &&  buf[2]=='1')led1=1;        //Le1 turns led1 on
                if(buf[0]=='L' &&  buf[1]=='e' &&  buf[2]=='0')led1=0;        //Le0 turns led1 off
                i=0;                                                      //reset the index and start over
            }

        }
    }
}

Hi Mr. Gorazd,

You made it happen. It is working. I tried it with other Command patterns and all other ports. It is successfully working. Finally i can contact my mbed through USBSearial.

Another point, you said MBED COM port, is that UART tx,rx of the mbed? Do we have connect D+ ,D- to tx and rx of any UART terminal of mbed? Because i wanna try that code too, which you said will only work with COM port, not USBSerial.

And your English is so good, i wonder why are you worrying about that.

Thank you Mr. Gorazd and Mr.Erik for helping me through. Both of you gave me the idea of how it is done. You guys are wonderful. Thank you once again. :) :)

What Gorazd meant (I think) is that there are two USB serial options for the mbeds: One is the USBSerial option which you now have working. This is done with the D+ and D- pins, and then you directly connect your computer to the USB pins of the LPC1768.

Then there is what Gorazd called the mbed com port, which is the USB connector on your mbed board. This is connected via another microcontroller that among other things implement a Serial <> USB bridge. You talk to it with Serial(USBTX, USBRX). Both result in serial over USB, but the first one the USB part is done by the LPC1768, the second one the LPC1768 just uses its UART to send serial messages, which are by anothr IC converted to USB.

Thank you Mr. Erik. I'll look forward in that. But any micro-controller(which has UART) can do that?

With another IC added? Yes. But that other IC is required, you cannot connect a random microcontrollers UART to a USB connector.

On mbed it is done by a second microcontroller, which also allows the drag and drop programming. If you have a random other microcontroller, the FTDI chips are popular to convert Serial to USB: http://www.ebay.com/itm/FTDI-Basic-FT232R-FT232RL-Arduino-USB-to-RS232-TTL-Program-Download-/360717429961?pt=LH_DefaultDomain_0&hash=item53fc6f2cc9

Hi Mr.Erik, I got it. I understood. It is available in our institute and i'll try with that too. Thank you Erik.