Fix issue with CDC device demos causing broken communications when the device tries to send data before the host has set the line encoding.

1 files changed, 17 insertions, 2 deletions

diff --git a/Demos/Device/LowLevel/CDC/CDC.c b/Demos/Device/LowLevel/CDC/CDC.c
index 8a992c767..73b486ccd 100644
--- a/Demos/Device/LowLevel/CDC/CDC.c
+++ b/Demos/Device/LowLevel/CDC/CDC.c
@@ -49,6 +49,12 @@ CDC_Line_Coding_t LineCoding = { .BaudRateBPS = 9600,
                                  .CharFormat  = OneStopBit,

                                  .ParityType  = Parity_None,

                                  .DataBits    = 8            };

+							

+/** Indicates if the host has set the device line encoding. Until the line encoding is set by the host, the device should

+ *  not attempt to send any bytes.

+ */	 

+bool LineEncodingSet = false;

+

 

 #if 0

 /* NOTE: Here you can set up a standard stream using the created virtual serial port, so that the standard stream functions in

@@ -59,6 +65,9 @@ static int CDC_putchar(char c, FILE *stream)
 {	  

 	Endpoint_SelectEndpoint(CDC_TX_EPNUM);

 

+	if (!(LineEncodingSet))

+	  return -1;

+	

 	while (!(Endpoint_IsReadWriteAllowed()))

 	{

 		if (USB_DeviceState != DEVICE_STATE_Configured)

@@ -74,7 +83,10 @@ static int CDC_putchar(char c, FILE *stream)
 static int CDC_getchar(FILE *stream)

 {

 	int c;

-	  

+

+	if (!(LineEncodingSet))

+	  return -1;

+

 	Endpoint_SelectEndpoint(CDC_RX_EPNUM);

 	

 	for (;;)

@@ -216,6 +228,9 @@ void EVENT_USB_UnhandledControlPacket(void)
 

 				/* Read the line coding data in from the host into the global struct */

 				Endpoint_Read_Control_Stream_LE(LineCodingData, sizeof(CDC_Line_Coding_t));

+				

+				/* Indicate that the line encoding has been set, and the device may now send data */

+				LineEncodingSet = true;

 

 				/* Finalize the stream transfer to clear the last packet from the host */

 				Endpoint_ClearIN();

@@ -299,7 +314,7 @@ void CDC_Task(void)
 	{

 		ActionSent = false;

 	}

-	else if (ActionSent == false)

+	else if ((ActionSent == false) && LineEncodingSet)

 	{

 		ActionSent = true;