MC68181 Datasheet, PDF (45/119 Pages) Freescale Semiconductor, Inc – Advance Information ROAMING FLEX chip SIGNAL PROCESSOR

Freescale Semiconductor, Inc.
MC68181
FLEX Message Word Definitions
Table A-12 Secure Message Bit Definitions
Symbol
Definition
N
Message Number—When the system supports message retrieval, the system
controller assigns message numbers (for each paging address separately) starting at 0
and progressing up to a maximum of 63 in consecutive order. The actual maximum
roll over number is defined in the pager code plug to accommodate values set in the
system infrastructure. When message numbers are not received in order, the
subscriber should assume a message has been missed. The subscriber or the pager may
determine the missing message number(s) allowing a request to be made for retrieval.
When a normal unnumbered numeric message is received (message retrieval flag is
equal to 0), it is not to be included in the missed message calculation. This number is
also used to identify fragments of the same message. Multiple messages to the same
address must have separate message numbers.
s
Spare Bit—not used and set to 0
MESSAGE CONTENT
Starting with the first character of the second word in the message (and 1st character
of all remaining fragments), each 7-bit field represents Standard ASCII (ISO 646-
1983E) characters with options for certain International characters.
MESSAGE TERMINATION
The ASCII character ETX (03) should be used to fill any unused 7-bit characters in a
word.
FLEX Encoding and Decoding Rules
The encoding and decoding rules identify the minimum requirements that must be
met by the paging device, paging terminal, or other encoding equipment to properly
format a FLEX data stream for RF transmission and to successfully decode it.
FLEX ENCODING RULES
• The stability of the encoder clock used to establish time positions of FLEX
frames must be no worse than ±25 ppm (including worst case temperature
and aging effects).
• A maximum of two occurrences of an identical individual or radio group
address is allowed in any frame for unfragmented messages. This rule applies
across all phases in a multi-phase frame. For example, for decoding devices
that support any-phase addressing, an any-phase address may appear at once
in two different phases in a single multi-phase frame.
• Once an individual or radio group address is used to begin transmitting a
fragmented message, that same address must not be used to start a new
MOTOROLA
MC68181 Technical Data Sheet
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