Datasheet

MRF49XA
DS70590C-page 60 Preliminary © 2009-2011 Microchip Technology Inc.
FIGURE 3-11: INPUT POWER VS. ANALOG RSSI VOLTAGE
3.13.1 RELATIONSHIP BETWEEN RSSI
AND CLOCK RECOVERY
The DIO signal response time setting is configured
through RXCREG and has the following modes of
operation:
• Normal mode
• Slow mode
• Medium mode
•Fast mode
These operation modes are configurable through
BBFCREG.
In Medium mode, the DIO signal is active when the
CR_LOCK and the DRSSI or the DQI signals are high.
The DIO goes low when either the CR_LOCK turns
inactive, or the DRSSI or DQI signals go low. For more
details on DQI, see Section 3.11, Data Quality
Indicator.
3.13.2 RELATIONSHIP BETWEEN RSSI
AND AFC
The Keep Offset mode of automatic configuration of
AFC (i.e., AUTOMS1 = 1, AUTOMS0 = 1) is
recommended to be used when a receiver operates
with only one transmitter. After a complete measuring
cycle, the measured value is kept independent from
the state of the DIO signal. In this mode, the DRSSI
limit should be carefully selected to minimize the range
hysteresis.
The registers associated with RSSI are:
•STSREG (see Register 2-1)
• GENCREG (see Register 2-2)
• RXCREG (see Register 2-7)
• PMCREG (see Register 2-13)
TABLE 3-2: DIGITAL RSSI THRESHOLD LEVELS
RSSI Threshold DRSSIT2 DRSSIT1 DRSSIT0
Reserved 111
Reserved 110
-73 101
-79 100
-85 011
-91 010
-97 001
-103 000
0
0.2
0.4
0.6
0.8
1
1.2
-112 -102 -92 -82 -72 -62 -52 -42
Input Power (dBm)
RSSI (V)