Re: [Libusb-win32-devel] Full speed bandwidth?

[Stephan M. <ste...@we...>]

Here are some values I get with one of my test programs using 
the synchronous API and an old 8051 Cypress full speed chip 
(double buffering enabled, 64 bytes endpoint buffer):

- the second column is the transfer size in bytes
- the third column is the throughput in kbytes/s


bulk write      |     64 |   32
bulk write      |    640 |  312
bulk write      |   6400 |  892
bulk write      |  64000 | 1041
bulk write      | 640000 | 1031
bulk read       |     64 |   31
bulk read       |    640 |  312
bulk read       |   6400 |  893
bulk read       |  64000 | 1041
bulk read       | 640000 | 1031
interrupt write |     64 |   32
interrupt write |    640 |   56
interrupt write |   6400 |   61
interrupt write |  64000 |   62
interrupt write | 640000 |   62
interrupt read  |     64 |   31
interrupt read  |    640 |   56
interrupt read  |   6400 |   61
interrupt read  |  64000 |   62
interrupt read  | 640000 |   62

> 
> Hi, im trying to do large bulk transfers to a full speed USB device (12mbit)
> Yet even in a dead loop, at best iv gotten 1.6mbps (yes, bits per second) 
> with 2k transfer sizes. Think I might get any better with async? My device 
> atm is a pic18f4550 without ping pong buffers enabled but id assume I should 
> get better then 1.6mbps even without them (Unless maybe its stalling?) and 
> the pic isent actualy doing anything with the data. 64byte buffer on the pic 
> side
> Is async even complete enough to use at all? When is 1.0 due out anyway? And 
> I can't even seem to find any documenation about async :( I really don't 
> want to have to go to using the DDK directly.
> 
> 
> 
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