/* This construct implements pre-call polling to ensure the sending completes before the function
* returns. It provides simple coding while also taking advantage of the efficiencies of background
* processing. If a previous send operation is underway, this function does waste cycles polling,
* like xxxsendDataWaitTilDone(); however it's less likely to do so since much of the sending
* presumably took place in the background since the last call to xxxsendDataInBackground().
* The function also checks all valid return codes, and returns non-zero if an error occurred.
* It assumes no previous send operation is underway; also assumes size is non-zero.
* This call assumes a previous send operation might be underway; also assumes size is non-zero.
* Returns zero if send completed; non-zero if it failed, with 1 = timeout and 2 = bus is gone. */
BYTE hidSendDataInBackground (BYTE* dataBuf,
WORD size,
BYTE intfNum,
ULONG ulTimeout)
{
ULONG sendCounter = 0;
WORD bytesSent, bytesReceived;
while (USBHID_intfStatus(intfNum,&bytesSent,
&bytesReceived) & kUSBHID_waitingForSend){
if (ulTimeout && ((sendCounter++) > ulTimeout)){ /* A send operation is underway; incr counter & try again */
return ( 1) ; /* Timed out */
}
}
/* The interface is now clear. Call sendData(). */
switch (USBHID_sendData(dataBuf,size,intfNum)){
case kUSBHID_sendStarted:
return ( 0) ;
case kUSBHID_busNotAvailable:
return ( 2) ;
default:
return ( 4) ;
}
}
/* This construct implements post-call polling to ensure the sending completes before the function
* returns. It provides the simplest coding, at the expense of wasted cycles and potentially
* allowing MCU execution to become "locked" to the host, a disadvantage if the host (or bus) is
* slow. The function also checks all valid return codes, and returns non-zero if an error occurred.
* It assumes no previous send operation is underway; also assumes size is non-zero. */
BYTE hidSendDataWaitTilDone (BYTE* dataBuf,
WORD size,
BYTE intfNum,
ULONG ulTimeout)
{
ULONG sendCounter = 0;
WORD bytesSent, bytesReceived;
switch (USBHID_sendData(dataBuf,size,intfNum)){
case kUSBHID_sendStarted:
break;
case kUSBHID_busNotAvailable:
return ( 2) ;
case kUSBHID_intfBusyError:
return ( 3) ;
case kUSBHID_generalError:
return ( 4) ;
default:;
}
/* If execution reaches this point, then the operation successfully started. Now wait til it's finished. */
while (1){
BYTE ret = USBHID_intfStatus(intfNum,&bytesSent,&bytesReceived);
if (ret & kUSBHID_busNotAvailable){ /* This may happen at any time */
return ( 2) ;
}
if (ret & kUSBHID_waitingForSend){
if (ulTimeout && (sendCounter++ >= ulTimeout)){ /* Incr counter & try again */
return ( 1) ; /* Timed out */
}
} else {
return ( 0) ; /* If neither busNotAvailable nor waitingForSend, it succeeded */
}
}
}
/*----------------------------------------------------------------------------+
| Main Routine |
+----------------------------------------------------------------------------*/
VOID main(VOID)
{
WDTCTL = WDTPW + WDTHOLD; // Stop watchdog timer
Init_StartUp();
USB_init();
USB_setEnabledEvents(kUSB_VbusOnEvent + kUSB_VbusOffEvent + kUSB_UsbSuspendEvent + kUSB_UsbResumeEvent + kUSB_receiveCompletedEvent + kUSB_UsbResetEvent);
// Check if we're already physically attached to USB, and if so, connect to it
// This is the same function that gets called automatically when VBUS gets attached.
if (USB_connectionInfo() & kUSB_vbusPresent)
USB_handleVbusOnEvent();
while(1)
{
switch(USB_connectionState())
{
case ST_USB_DISCONNECTED:
__bis_SR_register(LPM3_bits + GIE); // Enter LPM3 w/interrupt
break;
case ST_USB_CONNECTED_NO_ENUM:
break;
case ST_ENUM_ACTIVE:
if(!bCommandBeingProcessed) // If no command is being processed, then make sure there's a rcv operation
{ // open to receive the start of the "packet"
if(!(USBHID_intfStatus(0,&x,&y) & kUSBHID_waitingForReceive)) // Only open it if we haven't already done so
if(USBHID_receiveData(buffer,1,0) == kUSBHID_busNotAvailable) // Start a receive operation for a single byte -- the "size" byte of the "packet"
{
USBHID_abortReceive(&x,0); // Abort receive
break; // If bus is no longer available, escape out of the loop
}
}
__bis_SR_register(LPM0_bits + GIE); // Wait in LPM0 until a receive operation has completed
if(bDataReceiveCompleted_event)
{
bDataReceiveCompleted_event = FALSE;
if(!bCommandBeingProcessed) // This means that the incoming byte is the start of the "packet" -- the "size" byte
{
if ((buffer[0]>=0x31) && (buffer[0]<= 0x39))
{
size = buffer[0]-0x30; // It's in ASCII, so convert it to a number
if(USBHID_receiveData(buffer,size,0) == kUSBHID_busNotAvailable) // And then open a rcv operation for that size
{
USBHID_abortReceive(&x,0); // Abort receive
break; // If bus is no longer available, escape out of the loop
}
bCommandBeingProcessed = TRUE; // Now we're waiting for the "data" part of the "packet"
}
else
{
strcpy(outString,"\r\nEnter a valid number between 1 and 9\r\n\r\n"); // Prepare the outgoing string
if(hidSendDataInBackground((BYTE*)outString,strlen(outString),0,0)) // Send the response over USB
{
USBHID_abortSend(&x,0); // Operation may still be open; cancel it
break; // If the send fails, escape the main loop
}
bCommandBeingProcessed = FALSE; // Now we're back to waiting for the "size" byte
}
}
else // This means that the incoming data is the "data" part of the "packet"
{
strcpy(outString,"\r\nI received your packet with size of "); // Prepare the outgoing string
c[0] = (char)(size+0x30); // Convert the size back to ASCII
c[1] = 0; // Convert the size back to ASCII
outString[64] = 0;
strcat(outString,c);
strcat(outString," bytes.\r\n\r\n");
if(hidSendDataInBackground((BYTE*)outString,strlen(outString),0,0)) // Send the response over USB
{
USBHID_abortSend(&x,0); // Operation may still be open; cancel it
break; // If the send fails, escape the main loop
}
bCommandBeingProcessed = FALSE; // Now we're back to waiting for the "size" byte
}
}
break;
case ST_ENUM_SUSPENDED:
__bis_SR_register(LPM3_bits + GIE); // Enter LPM3 w/interrupt
break;
case ST_ENUM_IN_PROGRESS:
break;
case ST_NOENUM_SUSPENDED:
__bis_SR_register(LPM3_bits + GIE);
break;
case ST_ERROR:
_NOP();
break;
default:;
}
} // while(1)
} //main()
