Re: [Pyusb-users] Cleverboard

[Wander L. <wan...@gm...>]

Read the the limit quantity of bytes. If there is less bytes, they
will be returned...

2008/12/19 Santiago Palomino Sanchez-Manjavacas <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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