CN8478 Datasheet, PDF (177/221 Pages) Conexant Systems, Inc – Multichannel Synchronous Communications Controller (MUSYCC)

CN8478/CN8474A/CN8472A/CN8471A
Multichannel Synchronous Communications Controller (MUSYCC™)
6.0 Basic Operation
6.4 Protocol Support
SS7 Signal Unit Error Rate
(SUERR) Interrupt
In the case of an SS7 SUERR, an error is detected in SS7 mode which caused a
counter for SS7 related errors to equal or exceed the permitted threshold value.
The threshold is stored on a per-channel group basis in the bit field SUET in a
Group Configuration Descriptor.
Reasons:
• A Short SS7 message increments the SS7 counter.
• An FCS error in the SS7 message increments the SS7 counter.
• An Octet alignment error in the SS7 message.
• Accumulation of 16 “octet count” type errors increments counter.
NOTE: Receiving 256 unerrored SS7 messages decrements the SS7counter.
Effects:
• The Interrupt Descriptor in Interrupt Queue with ERROR = SUERR,
DIR = 0 (if MSKSUERR = 0 in Receive Channel Configuration
Descriptor).
• The BLP scans for the opening flag of the next HDLC message.
• Simultaneously, DMAC checks for Message Descriptor ownership before
transferring received data to shared memory.
Channel Level Recovery Actions:
• None required.
6.4.9 Transparent Mode
MUSYCC supports a transparent mode where no distinction is made between
information and non-information bits in the data bit stream. This mode is
assigned on a per channel and direction basis by the bit field PROTOCOL in the
Channel Configuration Descriptor.
In transparent mode, the following characteristics apply:
• All data bits are transferred between shared memory and the serial
interface without protocol support such as those listed for the HDLC
mode.
• Host must maintain the necessary data transfer rates at all times by
providing Message Descriptors and data buffers for both the transmit and
receive channels.
• The host must always set the bit field EOM to 0 in each Transmit Buffer
Descriptor. Setting EOM to 1 causes indeterminate results. Due to
EOM = 0, the other Transmit Buffer Descriptor bit fields—IC, PADEN,
PADCNT, and REPEAT—are ineffective.
Unlike HDLC mode, MUSYCC does not poll a host-owned Transmit Buffer
Descriptor during transparent mode.
When the internal buffer is empty and no more transmit data is available from
shared memory (i.e., host-owned buffer), MUSYCC does the following:
1. Issues an ONR error.
2. Enters the channel deactivate state, sending idle code on the affected
channel.
100660E
Conexant
6-43