MPC8280 datasheet(705/1386 Pages) FREESCALE

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Serial Communications Controllers (SCCs)

MPC8280 PowerQUICC II Family Reference Manual, Rev. 1

Freescale Semiconductor

20-25

4. If an INIT TX PARAMETERS command was not issued in step 3, issue a RESTART TRANSMIT

command.

5. Set GSMR_L[ENT]. Transmission begins using the TxBD pointed to by TBPTR, assuming

the R bit is set.

20.3.7.2

Reset Sequence for an SCC Transmitter

The following steps reinitialize an SCC transmit parameters to the reset state:

1. Clear GSMR_L[ENT].

2. Make any modifications then issue the INIT TX PARAMETERS command.

3. Set GSMR_L[ENT].

20.3.7.3

General Reconfiguration Sequence for an SCC Receiver

An SCC receiver can be reconfigured by following these steps:

1. Clear GSMR_L[ENR]. The SCC receiver is now disabled and put in a reset state.

2. Modify SCC Rx parameters or parameter RAM. To switch protocols or restore Rx parameters to

their initial state, issue an INIT RX PARAMETERS command.

3. If the INIT RX PARAMETERS command was not issued in step 2, issue an ENTER HUNT MODE

command.

4. Set GSMR_L[ENR]. Reception begins using the RxBD pointed to by RBPTR, assuming

the E bit is set.

20.3.7.4

Reset Sequence for an SCC Receiver

To reinitialize the SCC receiver to the state it was in after reset, follow these steps:

1. Clear GSMR_L[ENR].

2. Make any modifications then issue the INIT RX PARAMETERS command.

3. Set GSMR_L[ENR].

20.3.7.5

Switching Protocols

To switch an SCC’s protocol without resetting the board or affecting other SCCs, follow these steps:

1. Clear GSMR_L[ENT, ENR].

2. Make protocol changes in the GSMR and additional parameters then issue the INIT TX and RX

PARAMETERS

command to initialize both Tx and Rx parameters.

3. Set GSMR_L[ENT, ENR] to enable the SCC with the new protocol.

20.3.8

Saving Power

To save power when not in use, an SCC can be disabled by clearing GSMR_L[ENT, ENR].

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