Hello

Anybody ran experiments with the MC 18F4550 or 2550 USB capable controllers 
and managed to acchieve good speed? I'm getting about 1000 messages per 
second in any mode (bulk, control or interrupt -- HID or not) and wondering 
how to get it to speak a little faster.

Thanks 

"CDESC" <f...@realitymedias.com> wrote in message 
news:CoMIj.21122$n...@weber.videotron.net...
> Hello
>
> Anybody ran experiments with the MC 18F4550 or 2550 USB capable 
> controllers and managed to acchieve good speed? I'm getting about 1000 
> messages per second in any mode (bulk, control or interrupt -- HID or 
> not) and wondering how to get it to speak a little faster.
>
> Thanks

I made a USB-Serial converter using the PICDEM FS USB board (and actually 
using the older PICDEM USB modified for full speed), and I am able to run 
it at 57.6 kB, or 4800 characters per second. But I'm not sure of the 
actual messages per second.

There are good discussions on this in the Microchip User's Forum

In the thread: http://forum.microchip.com/tm.aspx?m=321195 there is a 
discussion of isochronous data rate, and it appears that all FS USB modes 
work with 1 mSec time slices, each of which can transfer a packet of 1023 
bytes, for a maximum throughput of about 1,000,000 bytes per second. But 
apparently the 18F devices do not have enough RAM to support this.

Here is a useful table that was referenced on the forum. But read the 
thread for more info.

http://forum.microchip.com/upfiles.aspx/29174/B786CC91A5D747178A7BD31C6BF5B134.JPG

Paul 

Hi Paul. Thanks for the re. and for pointing out the thread.

It looks from the posts I saw there that the best this little beast can do 
is limited to a packet per frame (1 micro) period, even though
the protocol specifications states that control/bulk modes aren't tied to 
the endpoing poll (re)cycle delay.

Though I confirm I ran tests that showed about 4500 Pk/S (of 3 bytes each) 
using a control input (pc>pic) endpoint and a bulk out (pic>pc) endpoint. So 
pick your flavor;
- I am violating the protocol
- My test results are wrong
- There is light, and a way to do it... in the end

Whoever ran tests using full-speed & bulk and/or control transfer modes, 
your test results would be more than welcome.

Thanks.



"Paul E. Schoen" <p...@smart.net> wrote in message 
news:47f3e54f$0$17413$e...@news.coretel.net...
>
> "CDESC" <f...@realitymedias.com> wrote in message 
> news:CoMIj.21122$n...@weber.videotron.net...
>> Hello
>>
>> Anybody ran experiments with the MC 18F4550 or 2550 USB capable 
>> controllers and managed to acchieve good speed? I'm getting about 1000 
>> messages per second in any mode (bulk, control or interrupt -- HID or 
>> not) and wondering how to get it to speak a little faster.
>>
>> Thanks
>
> I made a USB-Serial converter using the PICDEM FS USB board (and actually 
> using the older PICDEM USB modified for full speed), and I am able to run 
> it at 57.6 kB, or 4800 characters per second. But I'm not sure of the 
> actual messages per second.
>
> There are good discussions on this in the Microchip User's Forum
>
> In the thread: http://forum.microchip.com/tm.aspx?m=321195 there is a 
> discussion of isochronous data rate, and it appears that all FS USB modes 
> work with 1 mSec time slices, each of which can transfer a packet of 1023 
> bytes, for a maximum throughput of about 1,000,000 bytes per second. But 
> apparently the 18F devices do not have enough RAM to support this.
>
> Here is a useful table that was referenced on the forum. But read the 
> thread for more info.
>
> http://forum.microchip.com/upfiles.aspx/29174/B786CC91A5D747178A7BD31C6BF5B134.JPG
>
> Paul
>