title: What is the effective maximum payload throughput for USB in Full Speed?
body: <p>USB Full speed has a speed of 12 MBit/second = 1,5 MByte/s.</p>
  
  <p>But within these 12 MBit also a lot of extra data is transmitted which is not payload, like token, endpoint address, CRC5, CRC16, Acknowledge, SOF + EOF packets, etc.. Additionally the bus manager reserves 10% of a frame for Control Transfers.</p>
  
  <p>See <a href="http://www.usbmadesimple.co.uk/ums_g_interrupt.gif" rel="nofollow">Interrupt Transfer</a>
  in <a href="http://www.usbmadesimple.co.uk/ums_3.htm" rel="nofollow">USB Made Simple Part 3</a></p>
  
  <p>When I have an USB endpoint in Interrupt mode with a polling interval of 1 ms then I can transmit 64 bytes per frame = 64kByte / second.</p>
  
  <p>But what if I have 2 endpoints with 1 ms polling?
  Then the host will poll both endpoints within 1 ms so I have a total throughput of 128 kByte/s? </p>
  
  <p>And when the host is polling 15 IN endpoints simulataneously that would result in 15 * 64 kByte = 960 kByte/s? </p>
  
  <p>(Let's suppose for simplicity that there are no OUT transfers)</p>
  
  <p>First question: 
  Although searching a lot I could not find a website talking about the maximum effective payload throughput at Full Speed.</p>
  
  <p>Second question:
  Full speed allows a maximum of 64 byte / packet and a minimum poll interval of 1 ms. If I want to transfer the maximum possible payload via IN transfer, should I use multiple endpoints and spread the data transmission over these endpoints? With how many endpoints do I get to the limit?</p>
  
  <p>Third question:
  I see that in a Bulk transfer the host requests IN data more often than once per millisecond. Does this mean that Bulk is faster than Interrupt transfer?</p>