Re: [Fx2lib-devel] Arming bulk end points early

[Dennis M. <de...@ub...>]

Eric Winsor wrote:
> Dennis Muhlestein wrote:
>   
>> Eric Winsor wrote:
>>   
>>     
>>> I have an application where I would like to ship a 512 byte bulk in 
>>> endpoint whenever the host asks for a packet.  The host will not know 
>>> what size the packet is so I am planning on the host asking for 512 
>>> bytes.  I just want to give the host whatever has accumulated in the 
>>> EP4FIFOBUF when the host requests the in packet of 512 bytes on EP4.
>>>   
>>>     
>>>       
>> I think you'll have to tell the fx2 via a vendor command or something 
>> that you'll be wanting the packet.  The fx2 can then arm the endpoint, 
>> and the PC can then read the data.  There is otherwise no notice given 
>> across the USB bus to whatever microprocessor that your program wants to 
>> read data.  The program will just timeout on the PC side if the endpoint 
>> isn't armed.
>>
>> Is that what you were wanting to get at?
>>   
>>     
> Yes.  The data comes in very intermittently and may never be 512 bytes 
> in size.  I want the host to be able to get it periodically and there 
> may not be anything there at times.
>   
You could investigate interrupt endpoints instead of bulk maybe?  Or 
possibly have a different vendor command that lets the PC know a 
status.. like whether or not there is any data to get.

-Dennis