Communication Processor Module
MOTOROLA
MPC823 USER’S MANUAL
16-405
SMC
COMMUNICATION
16
PROCESSOR
MODULE
16.11.7.6 SMC TRANSPARENT CONTROLLER PARAMETER RAM MEMORY MAP.
There is no protocol-specific parameter RAM for the SMC Transparent controller. Only the
general SMC parameter RAM is used, which is discussed in more detail in
16.11.7.7 SMC TRANSPARENT COMMANDS. You can program the CPM command
register (CPCR) with the following commands to transmit data.
STOP TRANSMIT—After the hardware or software is reset and the channel is enabled
in the SMCM–Transparent register, the channel is in the transmit enable mode and
starts polling the first buffer descriptor in the table. This command disables the
transmission of frames on the transmit channel. If the transparent controller receives
this command while transmitting a frame, it stops after the contents of the FIFO are
transmitted (up to 2 characters). The TBPTR is not advanced to the next buffer
descriptor, no new buffer descriptor is accessed, and no new buffers are transmitted for
this channel. The transmitter sends idles until the RESTART TRANSMIT command is
issued.
RESTART TRANSMIT—This command is used to begin or continue transmission from
the current TBPTR in the channel’s TX buffer descriptor table. When the channel
receives this command, it starts polling the R bit in the TX buffer descriptor. A serial
management controller expects this command after a STOP TRANSMIT command is
issued and the channel in the SMCMR is disabled or after a transmitter error occurs.
INIT TX PARAMETERS—This command initializes all the transmit parameters in this
serial channel parameter RAM to their reset state and should only be issued when the
transmitter is disabled. The INIT TX AND RX PARAMS command can also be used to
reset the transmit and receive parameters.
You can program the CPCR with the following commands to receive data.
ENTER HUNT MODE—This command forces a serial management controller to close
the current receive buffer descriptor if it is currently being used and to use the next
buffer descriptor in the list for any subsequently received data. If a serial management
controller is not in the process of receiving data, the buffer is not closed. Additionally,
this command causes the receiver to wait for a resynchronization before further
reception continues.
CLOSE RX BD—This command is used to force a serial management controller to
close the current receive buffer descriptor if it is being used and to use the next buffer
descriptor in the list for any subsequently received data. If a serial management
controller is not in the process of receiving data, no action is taken by this command.
INIT RX PARAMETERS—This command initializes all the receive parameters in this
serial channel’s parameter RAM to their reset state. It should only be issued when the
receiver is disabled. The INIT TX AND RX PARAMS command can also be used to
reset the receive and transmit parameters.