FX2LP Bulk OUT Transfer Followed by Bulk IN Transfer

Question: Can FX2LP perform a Bulk OUT transfer, and immediately after it has completed, follow with a Bulk IN operation? Is a provision necessary for some kind of handshaking between FX2LP and the host so as to ensure proper operation in this case?

 

Answer:

Yes, the FX2LP device can follow with an IN right after an OUT has been completed. Usually the code in TD_Poll is structured to handle INs and OUTs this way, but provided that there is a committed IN buffer, the FX2 (due to its smart SIE) will send the IN packet to the host automatically. If there is no data available, the FX2LP device will respond with a NAK handshake.