MC68181 Datasheet, PDF (113/119 Pages) Freescale Semiconductor, Inc – Advance Information ROAMING FLEX chip SIGNAL PROCESSOR

Freescale Semiconductor, Inc.
MC68181
Building a Fragmented Message
the All Frame Mode Register, then the FLEXchip IC returns to normal
operation.
4. The FLEXchip IC continues to decode all of the frames and passes any address
information, vector information and message information to the host followed
by a status packet indicating the end of the frame. If the message is indicated
as fragmented by the Message Continued Flag “C” in the Message Packet for
a Secure, Alphanumeric or Hex/Binary Message then the host remains in the
Receive mode expecting more information from the FLEXchip IC.
5. After the host receives the second and subsequent fragment with the Message
Continued Flag “C” = 1, it should decrement the All Frame mode counter by
sending an All Frame Mode Packet to the FLEXchip IC with the “DAF” bit =
1. Alternatively, the host may choose to decrement the counter at the end of
the entire message by decrementing the counter once for each fragment
received.
6. When the host receives a Message Packet with the Message Continued Flag
“C” = 0, it will send two All Frame Mode Packets to the FLEXchip IC with the
“DAF” bit = 1. The two packets decrement the count for the first fragment and
the last fragment. This decrements the All Frame mode counter to zero, if no
other fragmented messages, or temporary addresses are pending or the FAF
bit is clear in the All Frame Mode Register, and returns the FLEXchip IC to
normal operation.
7. The above process must be repeated for each occurrence of a fragmented
message. The host must keep track of the number of fragmented messages
being decoded and insure the all frame mode counter decrements after each
fragment or after each fragmented message.
Table C-4 Alphanumeric Message Without Fragmentation
PACKET
PACKET
TYPE
PHASE
All Frame
Counter
COMMENT
1st
ADDRESS 1
A
0
Address 1 is received
2nd
VECTOR 1
A
1
Vector = Alphanumeric Type
3rd
MESSAGE
A
1
Message Word received “C” bit = 0; No
more fragments are expected.
4th
TBD
0
Host writes All Frame Mode Packet to
the FLEXchip IC with the “DAF” Bit = 1
Note: TBD—Host Initiated Packet. The FLEXchip IC returns a packet according to Decoder-to-Host
Packet Descriptions on page B-27.
MOTOROLA
MC68181 Technical Data Sheet
C-9
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