Re: [avrdude-dev] new USB-based programmer with Igor USB

[Jeff Epler]

On Wed, Nov 26, 2003 at 04:25:37AM +0100, Jan-Hinnerk Reichert wrote:
> > The problem was the number of packets: even running over-clocked at
> > 12MHz, the Igor USB takes a considerable length of time to handle
> > one USB request.
> 
> AFAIK, this is not specific to Igor USB. The number of packets per 
> second is simply limited to 125 for some reason. Have read something 
> about this in the in the I/O-Warrior datasheet a few days ago. Can't 
> find anything about it in the USB spec.
> 
> However, this seems to fit with the timing data you give.
[...]
> If you don't use polling it should be two 4-byte-commands. 
[...]
> 
> IMHO this won't be acceptable for most people ;-(
> Just think of the programming times for larger projects.

Yeah, if this is a hard limit it would mean that even sending one full
command per USB request I could only program 62 bytes per second, giving
16 seconds per kilobyte.  To move beyond this would require putting a
lot of intelligence in the USB device, something that's beyond my
capabilities and desires.

Jeff