Date: Fri, 08 Apr 2005 16:47:43 -0700 From: Maksim Yevmenkin <maksim.yevmenkin@savvis.net> To: ticso@cicely.de Cc: David Gilbert <dgilbert@dclg.ca> Subject: Re: Tricky USB device. Message-ID: <4257181F.1040904@savvis.net> In-Reply-To: <20050408233301.GW96690@cicely12.cicely.de> References: <16982.46075.115518.130213@canoe.dclg.ca> <4256B5EB.9080506@savvis.net> <16982.47024.135663.645297@canoe.dclg.ca> <20050408190514.GS96690@cicely12.cicely.de> <16983.465.572693.73195@canoe.dclg.ca> <20050408233301.GW96690@cicely12.cicely.de>
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Bernd Walter wrote:
> On Fri, Apr 08, 2005 at 06:12:33PM -0400, David Gilbert wrote:
>
>> Bernd> Has this device multiple interfaces? e.g. one HID and
>> another Bernd> as described. I often thought about getting ugen
>> working at Bernd> interface level too.
>>
>> Here's the output of udesc_dump on it. Right now, using the
>> current version of libusb (not the version from ports), I can use
>> usb_interrupt_write(dev, 1, "MK255", 5, 0) to send data to it ---
>> and the data is sent --- at least lights on the USB hub flash. If
>> I replace '1' with anything else, it doesn't accept it. However,
>> it doesn't seem to have opened the relays.
>
> Yes - you must use 1 - there is only one out-endpoint. 0x81 is for
> receiving data and endpoint 0 is the mandandory control endpoint.
> Interrupt Endpoints are not variable in size. Both interrupt
> endpoints are 8 Bytes, so you must read and write exact 8 Bytes per
> transfer - 5 shouldn't work for USB compliant devices.
hmmm... i was always confused about bMaxPacketSize. i was thinking that
it limits the size of one usb transaction, and it could take several usb
transactions to transfer one data packet.
for example i have a bluetooth usb dongle that has
Standard Endpoint Descriptor:
bLength 7
bDescriptorType 05
bEndpointAddress 81 (in)
bmAttributes 03 (Interruput)
wMaxPacketSize 16
bInterval 1
and i certanly can receive data packets from this endpoint that are more
(and less) then 16 bytes in size. so, i would guess (and i might be
wrong) that it is ok to send/receive data packets that are not equal to
bMaxPacketSize in size.
max
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