MPC8280 datasheet(928/1386 Pages) FREESCALE

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Multi-Channel Controllers (MCCs)

MPC8280 PowerQUICC II Family Reference Manual, Rev. 1

29-38

Freescale Semiconductor

29.8.1.2

Global Transmitter Underrun (GUN)

A global underrun (GUN) event indicates that the MCC’s transmit FIFO array experienced an underrun

condition. This is not due to a lack of ready transmit buffer descriptors (as in the UN condition in an

interrupt queue entry); rather, it indicates a hardware latency issue which could be caused in several ways.

FISU

SS7 mode only: FISU transmission started. The CP has started automatic FISU transmission if the first

BD of frame does not have its ready bit set and the SEN_FISU bit is enabled in SS7_OPT register.

Please refer to SEN_FISU bit in Section 29.3.4.3, “SS7 Configuration Register—SS7 Mode.

SLIPE

Only used in conjunction with AAL1 CES. Slip End. Set when an MCC channel interworking with an ATM

channel exits the slip state (the connection’s CESAC falls to the MCC_Start threshold). At this point, the

transmitter stops sending the underrun template (or last buffer) and starts sending valid data.

—

Reserved, should be cleared.

SLIPS

Only used in conjunction with AAL1 CES.Slip Start. Set when an MCC channel interworking with an ATM

channel enters a slip state (the channel’s CESAC reaches the MCC_Stop threshold). At this point the

transmitter freezes and begins sending the underrun template (or last buffer) until CESAC falls to the

MCC_Start threshold.

Tx no data. The CP sets this flag if there is no data available to be sent to the transmitter. The transmitter

sends an ABORT indication and then sends idles.

TXB

Tx buffer. A buffer has been completely transmitted. TXB is set (and an interrupt request is generated)

as soon as the programmed number of PAD characters (or the closing flag, for PAD = 0) is written to

MCC transmit FIFO. This controls when the TXB interrupt is given in relation to the closing flag sent out

at TXD. Section 29.9.2, “Transmit Buffer Descriptor (TxBD)” describes how PAD characters are used.

—

Reserved, should be cleared.

—

Reserved, should be cleared. (If SS7 mode, refer to the following description.)

AERM

SS7 mode only: Alignment error rate monitor threshold (M value in SS7 channel-specific parameters)

has been reached.

NID

Set whenever a pattern that is not an idle pattern is identified.

IDL

Idle. Set when the channel’s receiver identifies the first occurrence of idle (0xFFFE) after any non-idle

pattern.

MRF

Maximum receive frame length violation. This interrupt occurs when more bytes are received than the

value specified in MFLR. This interrupt is generated as soon as the MFLR value is exceeded; the

remainder of the frame is discarded

RXF

Rx frame. A complete HDLC frame has been received.

BSY

Busy. A frame was received but was discarded due to lack of buffers.

RXB

Rx buffer. A buffer has been received on this channel that was not the last buffer in frame. This interrupt

is also given for different error types that can happen during reception. Error conditions are reported in

the RxBD.

16–17

—

Reserved, should be cleared.

18–25

Channel number. Identifies the requests channel index (0–255).

26–31

—

Reserved, should be cleared.

Table 29-19. Interrupt Circular Table Entry Field Descriptions (continued)

Bits

Name

Description

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