28500-DSH-002-C Datasheet, PDF (159/224 Pages) M/A-COM Technology Solutions, Inc. – Multichannel Synchronous Communications Controller

Basic Operations
8.3.4.2
Transmit Change Of Frame Alignment (COFA)
Reason:
• Signal failure, glitch, or realignment caused by the physical interface sourcing the TSYNC/STB input signal.
Effects:
• Causes serial interface to enter COFA condition until a TSYNC/STB pulse arrives and is followed by at least
one frame for this port, without another unexpected TSYNC/STB pulse.
• For every active channel on the respective port, TSLP places channels into the deactivate state, wherein TSLP
sends a repetitive all ones sequence.
• Transmit output is three-stated.
Channel Level Recovery Actions:
• Transmit channel complete reactivation is required.
8.3.5
Receive Errors
Receive errors are service-affecting and may require a corrective action by the Host to resume normal processing.
8.3.5.1
Receive Overflow [BUFF]
Same as HDLC mode.
Reasons:
• Degradation of Host subsystem performance.
• Shortage of shared memory buffers. The receive buffer CX28500 needs to fill is presently Host-owned.
• PCI bus congestion.
Effects:
• RxBUFF Interrupt (if BUFFIEN = 1 in Section 6.6.2).
• Data received during an overflow condition is discarded.
• Data in the internal FIFO is copied to shared memory, the Receive Buffer Status Descriptor is written with
ONR = HOST, EOM = 1, ERROR = BUFF (if INHRBSD = 0 in Section 6.6.4 and Section 6.7.4).
• If ERRIEN is set in Section 6.6.4 and Section 6.7.4, an RxERR interrupt is generated, indicating an RxBUFF
overflow.
• When the overflow condition ends (i.e., space becomes available in the channel FIFO), RSLP automatically
restarts data processing. However, RSLP ignores all time slots until reaching the time slot marked “first.”
• RDMA is not affected and continues shared memory buffer processing.
Channel Level Recovery Actions:
• If possible, increase internal FIFO size assigned to this channel. For this action, the channel must first be
deactivated.
• If necessary, alleviate PCI bus congestion.
• Notice that channel reactivation is not required.
28500-DSH-002-C
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