MPC8280 datasheet(879/1386 Pages) FREESCALE

879 / 1386 page

Serial Management Controllers (SMCs)

MPC8280 PowerQUICC II Family Reference Manual, Rev. 1

Freescale Semiconductor

28-25

describes how to safely disable and reenable the SMC. Simply clearing and setting TEN may not be

enough.

28.4.6

SMC Transparent Commands

Table 28-10 describes transmit commands issued to the CPCR.

Table 28-11 describes receive commands issued to the CPCR.

28.4.7

Handling Errors in the SMC Transparent Controller

The SMC uses BDs and the SMCE to report message send and receive errors.

Table 28-10. SMC Transparent Transmit Commands

Command

Description

STOP

TRANSMIT

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

mode and polls the first BD. This command disables transmission of frames on the transmit channel. If the

transparent controller receives this command while sending a frame, it stops after the contents of the FIFO are

sent (up to 2 characters). The TBPTR is not advanced to the next BD, no new BD is accessed, and no new

buffers are sent for this channel. The transmitter sends idles until a RESTART TRANSMIT command is issued.

RESTART

TRANSMIT

Starts or resumes transmission from the current TBPTR in the channel TxBD table. When the channel receives

this command, it polls the R bit in this BD. The SMC expects this command after a STOP TRANSMIT is issued.

The channel in its mode register is disabled or after a transmitter error occurs.

INIT TX

PARAMETERS

Initializes transmit parameters in this serial channel to reset state. Use only if the transmitter is disabled. The

INIT TX AND RX PARAMETERS

command resets transmit and receive parameters.

Table 28-11. SMC Transparent Receive Commands

Command

Description

ENTER HUNT

MODE

Forces the SMC to close the current receive BD if it is in use and to use the next BD for subsequent

data. If the SMC is not receiving data, the buffer is not closed. Additionally, this command causes the

receiver to wait for a resynchronization before reception resumes.

CLOSE RXBD

Forces the SMC to close the current receive BD if it in use and to use the next BD in the list for

subsequent received data. If the SMC is not in the process of receiving data, no action is taken.

iNIT RX

PARAMETERS

Initializes receive parameters in this serial channel to reset state. Use only if the receiver is disabled.

The INIT TX AND RX PARAMETERS command resets receive and transmit parameters.

Table 28-12. SMC Transparent Error Conditions

Error

Descriptions

Underrun

The channel stops sending the buffer, closes it, sets UN in the BD, and generates a TXE interrupt if it is

enabled. The channel resumes sending after a RESTART TRANSMIT command. Underrun cannot occur

between frames.

Overrun

The SMC maintains an internal FIFO for receiving data. If the buffer is in external memory, the CP

begins programming the SDMA channel when the first character is received into the FIFO. If a FIFO

overrun occurs, the SMC writes the received data character over the previously received character. The

previous character and its status bits are lost. Then the channel closes the buffer, sets OV in the BD,

and generates the RXB interrupt if it is enabled. Reception continues as normal.

MPC8280 Datasheet(PDF) 879 Page - Freescale Semiconductor, Inc

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