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USB client - why no event for packet received


#1

I noted USB streams define no event for received data.
Since USB com is packet based, it would be well suited for such an event.

Or?


#2

this has been asked before. Upshot is that at a hardware level it still needs to be polled, so eventing this wouldn’t improve much.


#3

Yes no receive events as the device (FEZ) doesn’t actually read any data on its own and so there is no such event.


#4

I see. Does that mean the FEZ only reads data from the host when I issue a read command?
So, until I call Read from the FEZ, the data stays at the host?


#5

We usually get this question for USB Host serial USB/CDC and you have to explicitly poll for data, no events.
In USB client, it is possible to get events when data is received. This is very tied with NETMF internally. There are no current plans to add it. But polling isn’t that bad…


#6

Now that I know about some cons of USB, I am wondering how Ethernet is implemented.

  1. Does FEZ read ethernet data in the background?
  2. Is there a limit on how much data is received in the background (assuming it does) - will data be discarded is not read by the application in “time”?
  3. Is the answer to the questions above platform dependent… so different for Panda II, EMX, ChipworkX

The answers to these questions will hopefully help me decide once an for all which interface to use between the PC an the Mac.

Thanks,
Mark


#7

Your question is nit related to the topic. Please start new thread so we can help you better