Motorola MPC8260 - Manual (Page 778)

28-20 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA
Part IV. Communications Processor Module
28.12.1 FCC Transmitter Full Sequence
For the FCC transmitter, the full disable and enable sequence is as follows.
1. Issue the STOP TRANSMIT command. This is recommended if the FCC is currently
transmitting data because it stops transmission in an orderly way. If the FCC is not
transmitting (no TxBDs are ready or the
GRACEFUL STOP TRANSMIT command has
been issued and completed), then the STOP TRANSMIT command is not required.
Furthermore, if the TBPTR is overwritten by the user or the INIT TX PARAMETERS
command is executed, this command is not required.
2. Clear GFMR[ENT]. This disables the FCC transmitter and puts it in a reset state.
3. Make changes. The user can modify FCC transmit parameters, including the
parameter RAM. To switch protocols or restore the FCC transmit parameters to their
initial state, the
INIT TX PARAMETERS command must be issued.
4. If an INIT TX PARAMETERS command was not issued in step 3, issue a RESTART
TRANSMIT command.
5. Set GFMR[ENT]. Transmission begins using the TxBD that the TBPTR points to as
soon as TxBD[R] = 1.
28.12.2 FCC Transmitter Shortcut Sequence
A shorter sequence is possible if the user prefers to reinitialize the transmit parameters to
the state they had after reset. This sequence is as follows:
1. Clear GFMR[ENT].
2. Issue the INIT TX PARAMETERS command. Any additional changes can be made now.
3. Set GFMR[ENT].
28.12.3 FCC Receiver Full Sequence
The full disable and enable sequence for the receiver is as follows:
1. Clear GFMR[ENR]. Reception is aborted immediately, which disables the receiver
of the FCC and puts it in a reset state.
2. Make changes. The user can modify the FCC receive parameters, including the
parameter RAM. If the user prefers to switch protocols or restore the FCC receive
parameters to their initial state, the
INIT RX PARAMETERS command must be issued.
3. Issue the ENTER HUNT MODE command. This command is required if the INIT RX
PARAMETERS command was not issued in step 2.
4. Set GFMR[ENR]. Reception begins immediately using the RxBD that the RBPTR
points to if RxBD[E] = 1.