Motorola MPC8260 User Manual
22-10
MPC8260 PowerQUICC II UserÕs Manual
MOTOROLA
Part IV. Communications Processor Module
Table 22-9 describes receive errors.
22.11 BISYNC Mode Register (PSMR)
The PSMR is used as the BISYNC mode register, shown in Figure 22-5. PSMR[RBCS,
RTR, RPM, TPM] can be modiÞed on-the-ßy.
RTR, RPM, TPM] can be modiÞed on-the-ßy.
Table 22-8.
Transmit Errors
Error
Description
Transmitter
Underrun
Underrun
The channel stops sending the buffer, closes it, sets TxBD[UN], and generates aTXE interrupt if it
is enabled. The channel resumes transmission after a
is enabled. The channel resumes transmission after a
RESTART
TRANSMIT
command is received.
Underrun cannot occur between frames or during a DLEÐXXX pair in transparent mode.
CTS Lost during
Message
Transmission
Message
Transmission
The channel stops sending the buffer, closes it, sets TxBD[CT], and generates a TXE interrupt if
not masked. Transmission resumes when a
not masked. Transmission resumes when a
RESTART
TRANSMIT
command is received.
Table 22-9.
Receive Errors
Error
Description
Overrun
The controller maintains a receiver FIFO for receiving data. The CP begins programming the SDMA
channel (if the buffer is in external memory) and updating the CRC when the Þrst byte is received in
the Rx FIFO. If an Rx FIFO overrun occurs, the controller writes the received byte over the
previously received byte. The previous character and its status bits are lost. The channel then closes
the buffer, sets RxBD[OV], and generates the RXB interrupt if it is enabled. Finally, the receiver
enters hunt mode.
channel (if the buffer is in external memory) and updating the CRC when the Þrst byte is received in
the Rx FIFO. If an Rx FIFO overrun occurs, the controller writes the received byte over the
previously received byte. The previous character and its status bits are lost. The channel then closes
the buffer, sets RxBD[OV], and generates the RXB interrupt if it is enabled. Finally, the receiver
enters hunt mode.
CD Lost during
Message
Reception
Message
Reception
The channel stops receiving, closes the buffer, sets RxBD[CD], and generates the RXB interrupt if
not masked. This error has the highest priority. If the rest of the message is lost, no other errors are
checked in the message. The receiver immediately enters hunt mode.
not masked. This error has the highest priority. If the rest of the message is lost, no other errors are
checked in the message. The receiver immediately enters hunt mode.
Parity
The channel writes the received character to the buffer and sets RxBD[PR]. The channel stops
receiving, closes the buffer, sets RxBD[PR], and generates the RXB interrupt if it is enabled. The
channel also increments PAREC and the receiver immediately enters hunt mode.
receiving, closes the buffer, sets RxBD[PR], and generates the RXB interrupt if it is enabled. The
channel also increments PAREC and the receiver immediately enters hunt mode.
CRC
The channel updates the CR bit in the BD every time a character is received with a byte delay of
eight serial clocks between the status update and the CRC calculation. When control character
recognition is used to detect the end of the block and cause CRC checking, the channel closes the
buffer, sets the CR bit in the BD, and generates the RXB interrupt if it is enabled.
eight serial clocks between the status update and the CRC calculation. When control character
recognition is used to detect the end of the block and cause CRC checking, the channel closes the
buffer, sets the CR bit in the BD, and generates the RXB interrupt if it is enabled.
Bit
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Field
NOS
CRC
RBCS RTR
RVD
DRT
Ñ
RPM
TPM
Reset
0
R/W
R/W
Addr
Figure 22-5. Protocol-Specific Mode Register for BISYNC (PSMR)