Using LUFA as CDC for String Transmission

Question

I'm trying to use my AT90USB162 (Minimus USB board) as a CDC for sending a constant string to an hyperterminal connected to a comport. So I got the demo code Demos/Device/ClassDriver/VirtualSerial and made some changes:

In makefile:

MCU = at90usb162
BOARD = MINIMUS
F_CPU = 16000000

In VirtualSerial.h:

• Removed all entries related to Joystick.h, since AT90USB162 does not have it
• Created the header of functon SendSpecificString() (in exchange of the old CheckJoystickMovement(), which was related to the Joystick.h)

In VirtualSerial.c:

From SetupHardware(): removed call to Joystick_Init(), so the new code is (without comments).

void SetupHardware(void)
{
    MCUSR &= ~(1 << WDRF);
    wdt_disable();
    clock_prescale_set(clock_div_1);
    LEDs_Init();
    USB_Init();
}

Removed the void CheckJoystickMovement(void) and created the void SendSpecificString(void), based on the first, but without the joystick stuffs:

void SendSpecificString(void)
{
    char*       ReportString  = "data packet";
    static bool ActionSent    = false;

    if ((ReportString != NULL) && (ActionSent == false))
    {
        ActionSent = true;
        fputs(ReportString, &USBSerialStream);
    }
}

And finally in main(): exchanged the CheckJoystickMovement() call to the void SendSpecificString() call.

int main(void)
{
    SetupHardware();
    CDC_Device_CreateStream(&VirtualSerial_CDC_Interface, &USBSerialStream);
    LEDs_SetAllLEDs(LEDMASK_USB_NOTREADY);
    sei();

    for (;;)
    {
        SendSpecificString();
        CDC_Device_ReceiveByte(&VirtualSerial_CDC_Interface);
        CDC_Device_USBTask(&VirtualSerial_CDC_Interface);
        USB_USBTask();
    }
}

So, code builds and I burn into AT90USB162 and enable it. The comport (#6 in my case) appears and I can connect to it from hyperterminal (I'm using HypoTerminal most of the times, but same result occurs with Microsoft Hyperterminal). When I connect to the comport, the terminal does not get stuck as expected, however I expected also that the string ReportString = "data packet" would appear continuously in hyperterminal, but actually nothing appears. Then, what would have I missed?

Thank you.

Answer 1

I just discovered that the problem was not with the fputs or the CDC_Device_SendString calls. The condition loop was not necessary, in this case is enough to make

void SendSpecificString(void)
{
    char*       ReportString  = "data packet\r\n";
    fputs(ReportString, &USBSerialStream);
}

That's it.