Re: [Pyusb-users] Cleverboard

[Santiago P. Sanchez-M. <sp...@gm...>]

Hi, The thing is that you can always send 64 bytes as normal packet, and in
some cases, do not use all of them.

Another approach es that the interrupt will trigger a bulk read of a
variable size determined by what the interrupt packet says. But in that
case, you will have several usb transactions, and the result might be
slower. You may have a mixed approach, in which the interrupt packet holds
64 bytes always, and sometimes it reflects the need for a bulk read. (For
longer commands).


On Thu, Dec 18, 2008 at 4:03 PM, Phil Hannent <ph...@ha...> wrote:

> Hello,
>
> I am trying to write a driver for an interactive whiteboard.
>
> The device needs to be put into a state that will get it sending the pen
> data.
>
> However I have been looking examples on the internet and when using
> interruptRead or bulkRead you have to specify the number of bytes you are
> expecting.
>
> There are 30+ commands in the protocol with the device with a length which
> will
> be unknown until I read the first byte.
>
> I want to have a control loop that will read the interrupt and respond to
> that
> data.  With a user interface sending change of state commands.
>
> Does anybody have an example of the use of interruptRead and
> interruptWrite?
>
> Regards
> Phil Hannent
>
>
>
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