Freescale Semiconductor PowerQUICC MPC885 Reference Manual page 743

26.5 SCC BISYNC Commands
Transmit and receive commands are issued to the CP command register (CPCR). Transmit commands are
described in Table 26-2.
Command
After hardware or software is reset and the channel is enabled in the GSMR, the channel is in
STOP TRANSMIT
transmit enable mode and starts polling the first BD every 64 transmit clocks. This command stops
transmission after a maximum of 64 additional bits without waiting for the end of the buffer and the
transmit FIFO to be flushed. TBPTR is not advanced, no new BD is accessed, and no new buffers
are sent for this channel. SYNC–SYNC or DLE–SYNC pairs are sent continually until a
TRANSMIT
transmission should stop. After transmission resumes, the EOT sequence should be the first buffer
sent to the controller.
Note that the controller remains in transparent or normal mode after it receives a
RESTART TRANSMIT
Stops transmission after the current frame finishes sending or immediately if there is no frame being
GRACEFUL STOP
sent. SCCE[GRA] is set once transmission stops. Then BISYNC transmit parameters and TxBDs
TRANSMIT
can be modified. The TBPTR points to the next TxBD. Transmission resumes when the R bit of the
next BD is set and a
Lets characters be sent on the transmit channel. The BISYNC controller expects it after a
RESTART
TRANSMIT TRANSMIT
a
STOP TRANSMIT
transmission from the current TBPTR in the channel's TxBD table.
Initializes all transmit parameters in the serial channel's parameter RAM to their reset state. Issue
INIT TX
only when the transmitter is disabled.
PARAMETERS
parameters.
Receive commands are described in
Command
Immediately resets the receive BCS accumulator. It can be used to reset the BCS after recognizing
RESET BCS
a control character, thus signifying that a new block is beginning.
CALCULATION
After hardware or software is reset and the channel is enabled in SCCM, the channel is in receive
ENTER HUNT
enable mode and uses the first BD. This command forces the controller to stop receiving and enter
MODE
hunt mode, during which the controller continually scans the data stream for an SYN1–SYN2
sequence as programmed in the DSR. After receiving the command, the current receive buffer is
closed and the BCS is reset. Message reception continues using the next BD.
Used to force the SCC to close the current RxBD if it is in use and to use the next BD for subsequent
CLOSE RXBD
data. If data is not being received, no action is taken.
Initializes receive parameters in this serial channel's parameter RAM to reset state. Issue only when
INIT RX
the receiver is disabled. An
PARAMETERS
Freescale Semiconductor
Table 26-2. Transmit Commands
is issued. A can be used when an EOT sequence should be sent and
STOP TRANSMIT
command.
RESTART TRANSMIT
or a
GRACEFUL STOP TRANSMIT
is issued and the channel is disabled in its SCCM. The controller resumes
INIT TX AND RX PARAMETERS
Table 26-3.
Table 26-3. Receive Commands
INIT TX AND RX PARAMETERS
MPC885 PowerQUICC Family Reference Manual, Rev. 2
Description
is issued.
command is issued, after a transmitter error occurs, or after
resets transmit and receive
Description
resets transmit and receive parameters.
SCC BISYNC Mode
RESTART
or
STOP TRANSMIT
STOP
26-5