68HC708KL8 Datasheet, PDF (127/246 Pages) Freescale Semiconductor, Inc – Microcontrollers

Universal Serial Bus Module (USB)
9.6.2 USB Interrupt Register 0
Address: $0039
Bit 7
6
5
4
3
2
1
Bit 0
Read: TXD0F
Write:
RXD0F
RSTF
SUSPND TXD0IE
0
0
RXD0IE
TXD0FR RXDOFR
Reset: 0
0
0
0
0
0
0
0
= Unimplemented
Figure 9-23. USB Interrupt Register 0 (UIR0)
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, a NAK handshake will be returned in the next OUT
transaction.
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.
MC68HC708KL8 — Rev. 2.1
Freescale Semiconductor
Universal Serial Bus Module (USB)
General Release Specification
127