Hello,
I am working on USB CDC communication with PC using virtual COM port and it works but I dont understand one line of code. I am using usb-device-cdc-serial-project-at91sam7s-ek-keil as template. My code is:
TRACE_CONFIGURE(DBGU_STANDARD, 115200, BOARD_MCK);
// If they are present, configure Vbus & Wake-up pins
PIO_InitializeInterrupts(0);
//Driver initialization
CDCDSerialDriver_Initialize();
//Connect if needed
VBUS_CONFIGURE();
//Loop
while (1) {
CDCDSerialDriver_Write("Ahoj\n\r\0",7, 0, 0);}
This code works and it sends string to terminal, but when i comment first line with TRACE_CONFIGURE, virtual com port is not opened and device is not recognized after connection to PC. Can somebody tell me why is it so? I dont need tracing in my app. (sorry if it is stupid question. I am very new to uControllers)

Hi, try to make this in the main while :

while (1){
// Device is not configured
if (USBD_GetState() < USBD_STATE_CONFIGURED) {

// Connect pull-up, wait for configuration
USBD_Connect();
while (USBD_GetState() < USBD_STATE_CONFIGURED);
}


if( USBState == STATE_SUSPEND ) {
TRACE_DEBUG("suspend !\n\r");
LowPowerMode();
USBState = STATE_IDLE;
}
if( USBState == STATE_RESUME ) {
// Return in normal MODE
TRACE_DEBUG("resume !\n\r");
NormalPowerMode();
USBState = STATE_IDLE;
}

CDCDSerialDriver_Write("Ahoj\n\r\0",7, 0, 0);
}

Maybe you have to wait till the usb bus is ready.
Regards, Toni.