EPXFIFOBCH/L Registers of FX2LP – KBA219002

Version 1
Created by content.librarian on Mar 23, 2017 11:02 PM. Last modified by content.librarian on Mar 23, 2017 11:02 PM.
Version 1
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    Question:

    What do the EPXFIFOBCH and EPXFIFOBCL registers contain and how can they be used? 

     

    Answer:

    The EPXFIFOBCH and EPXFIFOBCL registers contain the number of bytes received from the interface domain. One way of using it is to commit a short packet, which is sent from the external master at the end of a long transfer. To do this, use the following code snippet in TD_Poll of the slave firmware: 

    if( (( EPXFIFOBCH<<8) | (EPXFIFOBCL)) < 0x200) //if the packet is short(here x is the IN endpoint which //receives data from external master)

    {

                      SYNCDELAY;

                      EPXFIFOCFG = 0x00;                  //change from Auto mode to Manual mode

                      SYNCDELAY;

                      INPKTEND = 0x0X;                    //commit the short packet

                      SYNCDELAY;

                      EPXFIFOCFG = 0x0C;                  //back to Auto mode

                      SYNCDELAY;

    }

    Here, to commit the short packet the FIFO configuration is changed from Auto to Manual mode. Then, it is converted back to Auto mode if the master continues the long transfer.