FIFO byte count registers

Question: Explain the count value present in EPXFIFOBCH, EPXFIFOBCL registers.



The EPXFIFOBCH, EPXFIFOBCL registers keeps count of the number of bytes in the concerned endpoint received from the peripheral side. So, this register will not reflect bytes sourced by the 8051 CPU or bytes received from the host. The count only reflects the number of bytes in the endpoint as a consequence of that endpoint being under the control of the peripheral domain.