Communication Processor Module
16-370 MPC823e REFERENCE MANUAL MOTOROLA
USB
COMMUNICATION
16
PROCESSOR MODULE
L—Last
0 = This buffer does not contain the last character of the message.
1 = This buffer contains the last character of the message.
TC—Transmit CRC
This bit is only valid when the L bit is set. Otherwise, it is ignored.
0 = Transmit end-of-packet after the last data byte. This setting can be used for testing
purposes to send a bad CRC after the data.
1 = Transmit the CRC sequence after the last data byte.
CNF—Transmit Confirmation (Host)
This bit is only valid when the L bit is set. Otherwise, it is ignored. It only affects endpoints
that have the MF bit set in the endpoint configuration register.
0 = Continue to load the transmitter FIFO with the next packet. No handshake or
response is expected from the function for this packet.
1 = Wait for handshake or response from the function before starting the next packet
or if this is the last packet.
LSP—Low-Speed Transaction (Host)
0 = The following transaction is with the host or a full-speed device.
1 = The following transaction is with a low-speed device (required only for data buffers
containing a token)..
PID—Packet ID
This field is set by the software to indicate the packet type. It is only valid for the first buffer
descriptor of a packet.
0x = Do not append PID to the data.
10 = Transmit DATA0 PID before sending the data.
11 = Transmit DATA1 PID before sending the data.
NAK—NAK Handshake Received (Host)
This bit indicates that the endpoint has responded with a NAK handshake. The packet was
received error-free, however, the endpoint could not accept it. This bit is written by the USB
controller after it has finished transmitting the associated data buffer.
Note: You cannot set CNF to 0 for a token that must be followed by a data packet if the
data packet buffer descriptor is not ready.
Note: You must always set LSP to 0 in slave mode.
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