MC68181 Datasheet, PDF (106/119 Pages) Freescale Semiconductor, Inc – Advance Information ROAMING FLEX chip SIGNAL PROCESSOR

MC68181
Receiver Control
Freescale Semiconductor, Inc.
Automatic Receiver Warm Up Sequence
The FLEXchip IC allows for up to six steps associated with warming up the receiver.
When the FLEXchip IC automatically turns on the receiver, it starts the warm up
sequence 160 ms before it requires valid signals at the EXTS0 and EXTS1 input pins.
The first step of the warm up sequence involves leaving the receiver control lines in
the “Off” state for the amount of time programmed for “Warm Up Off Time”. At the
end of the “Warm Up Off Time”, the first warm up setting, if enabled, is applied to
the receiver control lines for the amount of time programmed for that setting. Each
subsequent warm up setting is applied to the receiver control lines for their
corresponding time until a disabled warm up setting is found. At the end of the last
used warm up setting, the “1600 sps Sync Setting” or the “3200 sps Sync Setting” is
applied to the receiver control lines depending on the current state of the FLEXchip
IC. The sum total of all of the used warm up times and the “Warm Up Off Time”
must not exceed 160 ms. If it exceeds 160 ms, the FLEXchip IC will execute the
receiver shut down sequence at the end of the 160 ms warm up period. The receiver
warm up sequence while decoding when all warm up settings are enabled.enabled is
shown in Figure C-1 below..
Receiver
Control
Line
Setting
Warm Up
Off Time
Off
Warm Up
Time 1
Warm Up
Setting 1
Warm Up
Time 2
Warm Up
Setting 2
160 ms
Warm Up
Time 3
Warm Up
Setting 3
Warm Up
Time 4
Warm Up
Setting 4
Warm Up
Time5
Warm Up
Setting 5
1600 sps or 3200 sps
Sync Setting
Possible
LOBAT
Check
Possible
LOBAT
Check
Possible
LOBAT
Check
Possible
LOBAT
Check
Possible
LOBAT
Check
Possible
LOBAT
Check
Figure C-1 Automatic Receiver Warm Up Sequence
EXTS1 & EXTS0
Signals are
Expected to be
Valid Here
AA1236
Host Initiated Receiver Warm Up Sequence
The host can cause the FLEXchip IC to warm-up the receiver in three ways:
• By turning on FLEXchip by setting the ON bit in the control packet
• By requesting a noise detect by setting the SND bit in the roaming control
packet
• BY requesting an A-word search by setting the SAS bit in the roaming control
packet
C-2
MC68181 Technical Data Sheet
MOTOROLA
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