Lpc2000

--- In lpc2000@yahoogroups.com, "nicolkb1" <nicolkb1@...> wrote:
>
> Help anyone,
> 
> We are in the process of developing a new USB Printer using an 
> LPC2148 processor.  
> 
> The USB Interface is configured just fine to use EndPoint 2 as a 
BULK 
> Transfer Endpoint and we are using Bi-directional protocol.
> 
> Using Keil USB routines which came with the MCB2140 development 
> prototyping hardware, we have been able to configure the hardware 
and 
> get the communication start up is fine.  
> 
> We have observed the first transaction across EndPoint2 is an IN 
> request, coming from the LPC2148.  We are puzzled by this, we would 
> have assumed the first transaction would have been an OUT request 
> from the Host side.
> 
> Is this a setup issue???
> 
> Since the application on the LPC2148 has no data to send it is not 
a 
> problem at first start.  However, after a couple of commands have 
> been processed, and their has been several USB Nak'd packets a 
> problem occurs.
> 
> The problem is occurs when the Host sends an OUT Command with the 
> expectation of getting Data returned, the USBPrint.sys and 
> application is looking for couple of bytes of data to be returned 
in 
> an IN Packet.  The problem is the LPC2148 resends the Last 
> Transmission to the Host again, on the IN request prior to the OUT 
> command.
> 
> Are we missing a setup condition, which configures the (IN before 
> OUT) request or (OUT before IN) request in the USB interface or the 
> LPC2148 USB controller setup??? 
> 
> Is their something which needs to be done to clear out the EndPoint 
2 
> Transmit data area in ram???
> 
> We sure would appreciate some insight from someone.
> 
> Keith and Dwight
>

I suggest you look at www.hhdsoftware.com for their USB monitor 
software.  This will decode most of the usb transactions.  That and a 
copy of the usb spec and you will be going in no time.  You can DL a 
time limited evaluation copy and solve you troubles right away.  I 
bought a copy and it didn't take long to pay for its self (our first 
problem was solved in about 10 minutes).  No idea what your 
engineering time costs, but the U$49 package can save you a lot of 
time...

Regards,
Ian