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CC112X/CC1175
SWRU295C
Page 57 of 108
8.5.2
RX Termination Based on CS
If
RFEND_CFG0.ANT_DIV_RX_TERM_CFG = 001b
the device will use the first RSSI sample to
determine if a carrier is present in the channel. If no carrier is present (
asserted), RX will terminate. The RSSI samples are continually evaluated, and if the RSSI level falls
below the threshold (programmed through the
register) RX will terminate if not sync is
found. This can be used to achieve very low power by reducing the time in RX mode to a minimum.
Figure 24 shows how RX mode will be terminated based on CS for different scenarios. Note that sync
detection will keep the radio in RX until the packet is received regardless of the state of the
RX
1
2
3
4
5
IDLE
14
RX_TIME_QUAL = 0
RFEND_CFG0.ANT_DIV_RX_TERM_CFG = 001b
CARRIER_SENSE
IDLE
15
16
RX
1
2
3
4
5
IDLE
14
RX_TIME_QUAL = 0
RFEND_CFG0.ANT_DIV_RX_TERM_CFG = 001b
CARRIER_SENSE
IDLE
15
16
Time [ms]
Time [ms]
RX
1
2
3
4
5
IDLE
14
RX_TIME_QUAL = 0
RFEND_CFG0.ANT_DIV_RX_TERM_CFG = 001b
CARRIER_SENSE
IDLE
15
16
Time [ms]
RX
1
2
3
4
5
IDLE
14
RX_TIME_QUAL = 1
RFEND_CFG0.ANT_DIV_RX_TERM_CFG = 001b
CARRIER_SENSE
IDLE
15
16
Time [ms]
RX terminated due to lack of carrier
RX terminated when carrier is no
longer present
RX terminated at RX timeout due to
no sync word found
(RX_TIME_QUAL = 0)
RX terminated when carrier is no
longer present (not terminated at RX
timeout since carrier is present at
that time and RX_TIME_QUAL = 1)
Figure 24: RX Termination Based on CS (RX Timeout = 10 ms)
RX termination based on CS can be used even if the RX termination timer is not used
(
RFEND_CFG1.RX_TIME = 111b
).
8.5.3
RX Termination Based on PQT
If
RFEND_CFG0.ANT_DIV_RX_TERM_CFG = 100b
the device will use the PQT indication to
determine if RX mode should be terminated or not. If no preamble is detected, RX will be terminated.
The PQT indication is continually evaluated, and if the PQT level falls below the threshold RX will
terminate if no sync is found. This can be used to achieve very low power by reducing the time in RX
mode to a minimum.
RX termination based on PQT can be used even if the RX termination timer is not used
(
RFEND_CFG1.RX_TIME = 111b
).