Dear Sirs,

I adapted the USB-CDC demo for AT91SAM7A3, taken from the lwIP_Demo_Rowley_ARM7, it works but then I modified the vUSBCDCTask function to implement a simple Echo for that I at the end of the for(;;) block:

while( xQueueReceive( xRxCDC, &ucByte, usbNO_BLOCK ) ){
xQueueSend( xTxCDC, &ucByte, usbNO_BLOCK );
}

Then I test the throughput but It is really slow (about 300 @ 115200baud nominal). I would like to know how to improve the responsiveness. Should I do everything in the ISR function? Or should I wake up a task from the ISR? And then, howto to make a task waits the receipt of data (from ISR)? I put xQueueReceive (....) with some delay (e.g. usbSHORT_DELAY), but in this case the task is polling the queue....

Thank you for your help

Try searching the forum for "circular buffer". You should find some helpful discussion.

Dear sir,

thank you for your answer. I had a look at the old messages, but I couldn't find any new ideas.
I followed the R.Barry instruction I had:
- an ISR routine collecting data from the hardware and then it puts them in a Queue;
- a task replying with a simple echo. But the throughput is near 300baud (or less..)..note that if I repeat more times an incoming character (eg. 2 times) I double the speed..4 times speedx4 etc..

I wonder if the bottleneck would be on the pc side...

I try to put everything in the ISR routine

Sorry but the last part of the message is:

....
I try to put everything in the ISR routine but I didn't have any improvement

Thanks for your help

Have you checked that your ISR time doesn't exceed
your timer tick?

No, I haven't. How can I do that?

I have one more question, can happen a task switch while ISR is executing?
I put the 'echo' in the ISR, which is a smal amount of code: get data from usb IN buffer and put it in the OUT buffer.

thank for your help

M