MPC8280 datasheet(959/1386 Pages) FREESCALE

959 / 1386 page

Fast Communications Controllers (FCCs)

MPC8280 PowerQUICC II Family Reference Manual, Rev. 1

Freescale Semiconductor

30-21

30.12.1 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.

30.12.2 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].

30.12.3 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.

30.12.4 FCC Receiver Shortcut Sequence

A shorter sequence is possible if the user prefers to reinitialize the receive parameters to the state they had

after reset. This sequence is as follows:

1. Clear GFMR[ENR].

MPC8280 Datasheet(PDF) 959 Page - Freescale Semiconductor, Inc

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