28560-DSH-001-B_15 Datasheet, PDF (213/274 Pages) M/A-COM Technology Solutions, Inc. – HDLC Controller

CX28560 Data Sheet
Counters
A.3
Counter Descriptions
A.3.1
A.3.1.1
Receive Counters
In the receive direction, the following counters are provided per channel:
• Octet counter:
– A count of all octets received for this channel. This count does not include
HDLC flags, abort sequences, or idle codes. The count does include FCS
bytes and message data of all messages received including errored
messages.
• Message counter:
– A count of all non-errored messages received for a channel. An errored
message would either fall into one of the categories below, or have been
discarded mid-message due to local conditions (i.e., due to a COFA or OOF
condition being detected or an internal FIFO overflow occurring). Errored
messages that are not discarded due to local conditions are counted in the
counters below.
• Alignment Error counter:
– A count of all messages that arrive containing an alignment error. An
message containing an alignment error is defined as a message that, after
removal of HDLC flags and HDLC zero insertions, contains a number of
bits not divisible by eight.
• FCS Error counter:
– A count of all messages that arrive containing an FCS error.
• Abort Condition counter:
– A count of all messages that arrive ending in an abort condition. In this
case, an abort condition is considered to be seven consecutive ones.
• Too Long counter:
– A count of all messages that arrive that are longer than the maximum
length. The maximum length of a received message can be adjusted by
selecting one of three 14-bit registers that define a limit for the maximum
number of bytes allowed in the message.
• Too Short counter:
– A count of all messages that are considered too short. A short message is a
message with less than the minimum of an 8-bit payload between two flags
(e.g., at least 3 message bytes must be received in 16-bit FCS). Too short
also includes errors such as Abort, COFA, OOF, Alignment and FCS in the
case that no data had yet been transferred to the Buffer Controller from the
RSLP.
Multiple Errors on A Single Message
Each message is only counted once according to the following priority:
1. Abort condition
2. Too long message
3. Message alignment error
4. FCS error
5. No error occurs
That is to say, a message containing both an FCS error and alignment error is counted
only once in the Alignment Error counter.
28560-DSH-001-B
Mindspeed Technologies™
A-3
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