MPC8280 datasheet(781/1386 Pages) FREESCALE

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SCC Transparent Mode

MPC8280 PowerQUICC II Family Reference Manual, Rev. 1

Freescale Semiconductor

24-7

Table 24-4 describes receive commands.

24.8

Handling Errors in the Transparent Controller

The SCC reports message reception and transmission errors using the channel buffer descriptors, the error

counters, and SCCE. Table 24-5 describes transmit errors.

RESTART

TRANSMIT

Reenables transmission of characters on the transmit channel. The transparent controller expects

it after a STOP TRANSMIT command is issued (at which point the channel is disabled in SCCM), after

a GRACEFUL STOP TRANSMIT command is issued, or after a transmitter error. The transparent

controller resumes transmission from the current TBPTR in the channel TxBD table.

INIT TX

PARAMETERS

Initializes all transmit parameters in the serial channel parameter RAM to reset state. Issue only

when the transmitter is disabled. INIT TX AND RX PARAMETERS resets receive and transmit

parameters.

Table 24-4. Receive Commands

Command

Description

ENTER HUNT

MODE

After hardware or software is reset and the channel is enabled, the channel is in receive enable

mode and uses the first BD in the table. ENTER HUNT MODE forces the transparent receiver to the

current frame and enter hunt mode where the transparent controller waits for the synchronization

sequence. After receiving the command, the current buffer is closed. Further data reception uses

the next BD.

CLOSE RXBD

Forces the SCC to close the RxBD if it is being used and to use the next BD for any subsequently

received data. If the SCC is not receiving data, no action is taken by this command.

INIT RX

PARAMETERS

Initializes all receive parameters in this serial channel parameter RAM to reset state. Issue only

when the receiver is disabled. INIT TX AND RX PARAMETERS resets receive and transmit parameters.

Table 24-5. Transmit Errors

Error

Description

Transmitter

Underrun

When this occurs, the channel stops sending the buffer, closes it, sets TxBD[UN], and generates a

TXE interrupt if it is enabled. Transmission resumes after a RESTART TRANSMIT command is received.

Underrun occurs after a transmit frame for which TxBD[L] was not set. In this case, only SCCE[TXE]

is set. Underrun cannot occur between transparent frames.

CTS Lost During

Message

Transmission

When this occurs, the channel stops sending the buffer, closes it, sets TxBD[CT], and generates the

TXE interrupt if it is enabled. The channel resumes sending after RESTART TRANSMIT is received.

Table 24-3. Transmit Commands (continued)

Command

Description

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