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NP1 Ethernet Receive Buffer


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#1 Bernd

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Posted 03 June 2013 - 03:34 PM

Hello,

does anybody know the size of the Transmit and Receive buffer of the NP1 ? I want to communicate via UDP with the NP1. The UDP packet has 512byte and so I  wonder this will work, or I have to take care to send only packets that are not larger as the receive buffer.

 

I read the documentation of the ARM7, but I don't understand the relationships of the fifo buffer with 28byte to the receive buffer. The receive buffer consist of several buffers with a length of 128byte. But how does this buffer communicate with the fifo buffer ?



#2 ziggurat29

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Posted 03 June 2013 - 11:14 PM

I don't think the ethernet has a buffer per se like, for instance, the serial port.  Looking at the source, the packet buffers are allocated as needed via netbuf_alloc(), which takes a size parameter.

 

IP fragmentation will handle reconstituting your UDP datagram up to it's max size (64k), from the much smaller IP fragments.  Obviously, achieving that maximum will be a stretch for the netduino, but my point is that limit is a soft limit.  I would think you'd be fine with a couple K, and it would be interesting to hear results from some practical tests.



#3 Bernd

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Posted 04 June 2013 - 08:49 PM

Ok

Thanks ziggurat29 for your fast answer. I have googled about the netbuff_alloc() and I think you are right. At the moment I am very busy but than I have free time, I will make some tests about that with different size of packets. I will give you a feedback.






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