topic Re: Which USB communication class to use for optimum speed ? in LPCXpresso IDE

Which USB communication class to use for optimum speed ?

lpcware — Wed, 15 Jun 2016 22:42:02 GMT

Content originally posted in LPCWare by iClectic on Thu Jun 10 09:51:55 MST 2010
Hi,

I've developed a small board based on the LPC1343 that currently communicate back and forth with the host thanks to the built-in HID class driver. It works perfectly fine, but the maximum bandwidth seems limited to 64kb/s.

I'm no USB expert and I'm wondering what might be the other (and easy to implement) alternatives with the LP1343 that could bump up that bandwidth.

Any suggestion/recommandation ? I've looked at the CDC, but was not able to see what's the maximum speed achievable with the LPC1343.

Thanks in advance for your help,

Richard

Re: Which USB communication class to use for optimum speed ?

lpcware — Wed, 15 Jun 2016 22:42:03 GMT

Content originally posted in LPCWare by domen on Thu Jun 10 14:11:18 MST 2010
Yup, HID (or actually, interrupt transfers) is limited to 64 B every second (per endpoint?).

With simple CDC code I made it >400kB/s (no optimizations, just a bit modified example); I recall some guy from Hitex telling he got it to ~900kB/s.

Re: Which USB communication class to use for optimum speed ?

lpcware — Wed, 15 Jun 2016 22:42:04 GMT

Content originally posted in LPCWare by iClectic on Thu Jun 10 14:25:25 MST 2010
Hi Domen,

400Kb/s would be plenty enough :D
Would you mind sharing your modified version with me ?
Thanks in advance,

Richard

Re: Which USB communication class to use for optimum speed ?

lpcware — Wed, 15 Jun 2016 22:42:04 GMT

Content originally posted in LPCWare by domen on Sun Jun 13 11:04:35 MST 2010

Quote: iClectic

Would you mind sharing your modified version with me ?

It'd only confuse you, because some parts were rewritten etc.

I just cut out the serial.c code, and filled the outgoing circular buffer in main (while(1)) loop.

Re: Which USB communication class to use for optimum speed ?

lpcware — Wed, 15 Jun 2016 22:42:05 GMT

Content originally posted in LPCWare by amendae on Sun Jul 18 20:08:56 MST 2010

Quote: domen
It'd only confuse you, because some parts were rewritten etc.

I just cut out the serial.c code, and filled the outgoing circular buffer in main (while(1)) loop.

Well, actually with CDC, I personally barely reach 40KB/s...which is slower than the 64KB/s that HID brings out of the box :( I might be doing something wrong. I would also appreciate some guidance here, especially if someone managed to reach 900Kb/s.