Hitachi H8S/2215 Series Hardware Manual page 552

(2) Data Stage (Control-In)
The firmware first analyzes command data from the host in the setup stage, and determines the
subsequent data stage direction. If the result of command data analysis is that the data stage is
in-transfer, one packet of data to be sent to the host is written to the FIFO. If there is more data
to be sent, this data is written to the FIFO after the data written first has been sent to the host
(EP0iTS of UIFR0 is set to 1).
The end of the data stage is identified when the host transmits an OUT token and the status
stage is entered.
Rev. 3.0, 10/02, page 494 of 686