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USB Low-Full-High Speed Peripherals

Not applicable

 My company has been using an FX2LP with the same code for many years.


Recently we did a board spin(just got the prototypes).  Theoretically the FX2LP is wired on the board the same as before.  




The PC software is able to connect to the cypress.


The FX2LP correctly enumerates the device.


The PC successfully sends commands to the FX2LP, that are echoed over RS232 for debugging.


The FX2LP thinks it successfully sent data back to the PC, the RS232 debugging output shows function success.


The PC times out when calling m_ep8In->XferData.  Using the software USBlyzer, I see no USB packets coming from the FX2LP.




1) When sending works and receiving fails, what chip connections / pins should we check first?


2) Is there a standard diagnostic to exercise Cypress / PC communication?







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