MC908JB16DWE Datasheet, PDF (187/332 Pages) Freescale Semiconductor, Inc – Microcontrollers

Universal Serial Bus Module (USB)
TXD0F — Endpoint 0 Data Transmit Flag
This read-only bit is set after the data stored in endpoint 0 transmit
buffers has been sent and an ACK handshake packet from the host is
received. Once the next set of data is ready in the transmit buffers,
software must clear this flag by writing a logic 1 to the TXD0FR bit. To
enable the next data packet transmission, TX0E also must be set. If
the TXD0F bit is not cleared, a NAK handshake will be returned in the
next IN transaction.
Reset clears this bit. Writing to TXD0F has no effect.
1 = Transmit on endpoint 0 has occurred
0 = Transmit on endpoint 0 has not occurred
RXD0F — Endpoint 0 Data Receive Flag
This read-only bit is set after the USB module has received a data
packet and responded with an ACK handshake packet. Software
must clear this flag by writing a logic 1 to the RXD0FR bit after all of
the received data has been read. Software also must set the RX0E bit
to 1 to enable the next data packet reception. If the RXD0F bit is not
cleared, the USB will respond with a NAK handshake to any
endpoint 0 OUT tokens; but does not respond to a SETUP token.
Reset clears this bit. Writing to RXD0F has no effect.
1 = Receive on endpoint 0 has occurred
0 = Receive on endpoint 0 has not occurred
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Universal Serial Bus Module (USB)
Technical Data
187