28560-DSH-001-B_15 Datasheet, PDF (144/274 Pages) M/A-COM Technology Solutions, Inc. – HDLC Controller

The CX28560 Memory Organization
CX28560 Data Sheet
5.9.2
Transmit POS-PHY Data Bus
The system provides data to the CX28560 over a 32 bit POS-PHY bus. When and how
much data is to be provided to the CX28560 can be calculated using the information
received by the system over the Flow Conductor Bus. All fragments sent to the CX28560
by the system should be of equal length (as configured) except for the last fragment which
contains only the last bytes of the message and, therefore, may contain as little as 0 bytes
of actual data.
Table 5-55. CX28560 Transmit Data Header Format
Bit Field Name Value
Description
31:27
26:16
15
RSVD
CHANNEL
COMVALID
14:12 IC
11:4 PADCNT
0 Reserved.
— Logical Channel Number.
Command Valid Bit
This bit is set on the last fragment of a packet to indicate that the Idle Code and Pad Count
fields are valid.
0 Command Bits Not Valid.
1 Command Bits Valid.
0 Inter-message Idle Code Encoding.
0 HDLC – FLAGS (0x7E)
TRANSPARENT – ALL ONES (0xFF)
1 HDLC – ALL ONES (0xFF)
TRANSPARENT – FLAGS (0x7E)
2 ALL ZEROS (0x00)
3 Reserved.
— The minimum number of inter-message idle code bytes to be transmitted.
HDLC:
PADCNT indicates the minimum number of idle codes to be inserted between the closing
flags and the next opening flag (0x7E).
PADCNT = 0, yields a shared flag between two successive messages.
PADCNT = 1, yields the bit pattern:
<message><0x7E><0x7E><message>
PADCNT = 2, yields the bit pattern:
<message><0x7E><IC><0x7E><message>
TRANSPARENT:
Indicates the (minimum number + 1) of idle codes to be inserted between successive
messages.
PADCNT = 0, one Idle Code byte will be transmitted between messages
<message><IC><message>
3 ABORT
—
—
2:0
RSVD
PADCNT = 1, two Idle Code bytes will be transmitted between messages
<message><IC><IC><message>
======
NOTE(S): There is no indication if more than PADCNT number of idle codes are inserted.
0 No Abort
Finish the message in an orderly manner
1 Abort Signal
Abort the present message by adding at least 7 ones. Continue with next message as usual
(i.e., no deactivation).
— Reserved.
5-54
Mindspeed Technologies™
28560-DSH-001-B
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