Hi,
I have a working (mostly) project that takes text from the PC, one byte at a time, and echoes it back to the PC. It does this in generic HID, using the 8 byte reports as defined in AN82072. I have weird behavior though, which I would like to fix. The device displays the string that it receives to an LCD; the LCD is helpful for testing. It seems to receive the overwhelming majority of bytes OK. But on the PC side, the IN side, the text comes back somewhat garbled. I have largely mitigated this, but I don't understand why it is happening. I can't reliably create a device with this USB if moving a block around changes it from working to not without rhyme or reason.
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USB_Start(0,USB_DWR_VDDD_OPERATION);
#define UnassignedAddress 0
while(USB_deviceAddress == UnassignedAddress)
{
// Wait for device address to be assigned
}
while(!(USB_GetConfiguration()));
for(;;)
{
uint8 interruptState;
interruptState = CyEnterCriticalSection();
/* Place your application code here. */
// the primary USB send and receive function
OUT_COUNT = 0;
if(USB_IsConfigurationChanged()) //make happen every time
{
//USB_GetInterfaceSetting(0); // works without this line???
USB_LoadEP(IN_ENDPOINT, IN_Data_Buffer, 8);
USB_ReadOutEP(OUT_ENDPOINT, OUT_Data_Buffer, OUT_COUNT);
USB_EnableOutEP(OUT_ENDPOINT);
}
// //////////////////////////// WHY DOES THIS CHANGE WORK? ///////////////////////////////////////////
// --------------------------------------------------------------------------------------------------------------------------------
// moved the following block down below:
#############################################################################
/*
if ((USB_GetEPState(IN_ENDPOINT) == USB_IN_BUFFER_EMPTY ) ) //Data to send
{
USB_LoadEP(IN_ENDPOINT, NULL, 8);
//USB_EnableOutEP(OUT_ENDPOINT);
}
*/
#############################################################################
// --------------------------------------------------------------------------------------------------------------------------------
if(USB_GetEPState(OUT_ENDPOINT) == USB_OUT_BUFFER_FULL) /// Data to Receive
{
OUT_COUNT = USB_GetEPCount(OUT_ENDPOINT);
USB_EnableOutEP(OUT_ENDPOINT);
}
if (OUT_COUNT != 0)
{
char tempChar = (char)OUT_Data_Buffer[0];
// this loop resets the OUT line on LCD
// once it is full and more text has arrived
if(textOutLength > maxLength)
{
textOutLength = 0;
//LCD_Position(1u,0u);
// this loop blanks the OUT line on LCD
// it is 21 elements long, even though the screen is 20
// b/c I append a \0 when sending the text from PC
for(int z = 0; z <= 20; z++)
{
textOut = ' ';
}
int bob = 0;
}
if (tempChar != 0)
{
textOut[textOutLength] = tempChar;
textOutLength = textOutLength + 1;
IN_Data_Buffer[0] = OUT_Data_Buffer[0];
if(textInLength > maxLength)
{
textInLength = 0;
textInIndex = 0; // should I update this one here???
for(int i = 0; i < 20; i++)
{
textIn = ' ';
}
}
textIn[textInLength] = IN_Data_Buffer[0];
textInLength = textInLength + 1;
}
}
// --------------------------------------------------------------------------------------------------------------------------------
// This block was moved down here from the marked area above
if ((USB_GetEPState(IN_ENDPOINT) == USB_IN_BUFFER_EMPTY ) ) //Data to send
{
USB_LoadEP(IN_ENDPOINT, NULL, 8);
//USB_EnableOutEP(OUT_ENDPOINT);
}
// --------------------------------------------------------------------------------------------------------------------------------
CyExitCriticalSection(interruptState);
}
}
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Maybe it is the addition of a delay between the OUT and IN??? But I've tried the old version with small CyDelay(1) (note that the interrupt timing is 100ms, so a 1ms delay shouldn't be consequential) between GetEpState() blocks, to no effect?
