cx28560 Mindspeed Technologies, cx28560 Datasheet - Page 162

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

Basic Operations
7.2.4
7.2.5
7.2.5.1
7.2.5.2
7-4
Zero-Bit Insertion/Deletion
Message Configuration Bits—HDLC Mode
In cases where received idle codes transition to an abort code, an interrupt descriptor
is generated toward the host (if enabled in RSLP Channel Configuration register—see
Chapter
abort codes are discarded.
NOTE:
The CX28560 provides zero-bit insertion and deletion when it encounters five
consecutive 1s within a frame. In the receiver, the zero-bit is removed (discarded). In
the transmitter, the zero-bit is inserted after each sequence of five 1s.
The last fragment of a transmit message is prefixed by a fragment header that contains
message configuration bits to specify what data pattern is transmitted after the end of
a current message and its respective closing flag have been transmitted. The bits are
specified as follows:
NOTE:
Idle Code
The Idle Code (IC) specification allows one of a set of idle codes to be chosen to be
transmitted after the current message in case the next message is not available to be
transmitted or intermessage pad fill is requested via PADCNT.
Intermessage Pad Fill
The pad count (PADCNT) specification allows pad fill octets (a sequence of one or
more specified idle codes) to be transmitted between messages. PADCNT is the
minimum number of fill octets to be transmitted between the closing flag of one
message and the opening flag of the next message in the following manner:
• Idle Code specification, IC
• Inter-message Pad Fill Count, PADCNT
• Send an Abort Sequence, ABRT or assert ERR line on POS-PHY
1.
2.
3.
1.
2.
3.
4.
Seven 1s are the abort condition the CX28560 checks for while receiving a
message, but the criteria for detection and generation of a Change To Abort
Code interrupt is equal to 14 consecutive 1s.
Message configuration bits are also used in Transparent mode with slightly
different meanings. For details, see Idle Code.
IC = 0: Flag pad fill
IC = 1: All ones pad fill
IC = 2: All zeroes pad fill
PADCNT = 0: Shared open/close flag
PADCNT = 1: Separate open/close flags, no idle code
PADCNT = 2: Separate open/close flags, at least one idle code
Etc.
5.0), indicating the informational event Change To Abort Code. All received
Mindspeed Technologies™
Advance Information
CX28560 Data Sheet
28560-DSH-001-B