cx28560 Mindspeed Technologies, cx28560 Datasheet - Page 83

• Manufacturer Part Number: cx28560
• Description: Hdlc Controller
• Manufacturer: Mindspeed Technologies

CX28560 Data Sheet
4.6.3
4.6.4
28560-DSH-001-B
Out Of Frame (OOF)/Frame Recovery (FREC)
General Serial Port Interrupt
In the transmit direction, the TSLP aborts the messages, immediately deactivates
the relevant channels, and reports the deactivation to the TBUFFC. The TBUFFC
flushes the channels buffer and waits for an activation command. As a recovery
channel action, the host must re-activate the channel upon termination of the
COFA condition. COFA detection is not applicable in unchannelized mode. When
COFA condition occurs, the transmit output is three-stated. If operating in T1
mode, the F-bit may not be three-stated after a COFA condition.
The Receiver Out-Of-Frame (ROOF) signal is asserted by the serial interface
sourcing the channelized data to the CX28560. This signal indicates that the
interface device has lost frame synchronization.
In the case of multiplexed E1 lines (2xE1, 4xE1), any given port ROOF signal
may be asserted and deasserted as the time slots are received from an Out-Of-
Frame (OOF) E1 followed by an in-frame E1. ROOF assertion is detected by the
Receiver Serial Interface (RSIU). If ROOF is asserted (transitions from low to
high) and OOFIEN bit field in the RSIU Port Configuration Descriptor is set, an
OOF interrupt is generated toward the host.
For each receive HDLC message that encountered an OOF condition, an end of
message status is prepared with the error encoding set to OOF and passed to the
system. For transparent mode channels, the OOF causes the data that is being
transferred to the host to be replaced by an all 1s sequence. No special actions are
taken in this case, and the host must rely on the OOF interrupt to learn about the
OOF.
One to three time slots after ROOF is asserted, the CX28560 generates an
interrupt descriptor with the OOF error encoded in the Interrupt Status
Descriptor. While ROOF is asserted, if OOFABT bit field in the RSIU Port
Configuration Descriptor is set, the receive process is disabled. Thus, the
CX28560 terminates any active messages for all active channels operating over
the port; otherwise, the receive process is enabled.
Notice that the OOF signal is examined on a per-time slot basis. Therefore, OOF
assertion affects only those logical channels mapped to time slots where OOF is
asserted. The remaining time slots on the same serial port are not affected by the
OOF assertion on a specific time slot.
As ROOF is deasserted, the CX28560 immediately restarts normal processing on
all active channels. One to three time slots after deassertion of ROOF is detected,
the CX28560 generates an interrupt descriptor with the FREC (Frame Recovery)
interrupt encoding if the interrupt is not masked (OOFIEN = 1, RSIU Port
Configuration Descriptor).
ROOF signal can be used as a general serial port interrupt (SPORT). If OOFABT
is zero, OOFIEN is set and ROOF signal deasserts, SPORT interrupt is generated,
and the data stream processing is not affected. When ROOF transitions from low
to high, the SPORT interrupt is cleared.
Mindspeed Technologies™
Advance Information
CX28560 Serial Interface
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